I'll preface this part with a warning. If I did it again, I don't think I'd do it this way.

The first thing I did was stack the frame, control panel, and the sides together, then I glued & screwed them together.  Then I attached each individual panel I'd previously built, along with furring strips to secure them in place

My badly-planned initial assembly step
If I do it again, my first step would be to attach the furring strips to both side pieces, and ensure that they are placed symmetrically on both sides.  The problem I ran into was that it was difficult to perfectly line up the furring strips on both sides.  On my final assembly, I have some panels that are slightly crooked.  I'd guess that I might be the only person to notice it, but it's annoying nonetheless.

For my assembly, I countersunk and screwed each piece into its respective furring strip from the outside.  Then I had to fill & sand each screw hole.  I'm sure other people could find more intelligent ways to do this without needing to fill dozens of screw holes.

Rear view.  I used the button-hole drill bit to add ventilation holes.
There's a computer living inside the cabinet, and computers create heat.  So, I also made sure to provide a bit of ventilation.

Front view.  Assembled and prepped for painting.
Once everything was assembled, I also routed the slot for the T-Molding.  I used a 1/16" width & 9/16" depth bit.  Because my router was old & rickety, I had to constantly keep an eye on where the slot was being routed, since my bit wanted to keep walking out of the collet.

Routing the T-Molding Slot

I had previously attached the artwork to the admin panel, so I made sure to tape this off before painting the entire cabinet.  I also previously painted the base.  I don't know why I previously painted the base. ¯\_(ツ)_/¯

With everything prepped & assembled, I first primed the entire cabinet with Kilz primer...

...and then I painted it with two coats of Rustoleum black satin paint.  I chose Rustoleum because it's enamel & not a latex paint, which means it's more durable once it dries.  Also of note: when painting & priming, I used foam rollers for the easy-to-paint areas, and a spray can for the not-so-easy areas with lots of edges & corners.

Below is a grab-bag of random features I included in my design:

The control panel is removable and can be placed on top of the cabinet.

I included a plain flat version of the control panel to allow mouse & keyboard gaming.  This also fits on top of the cabinet, and is swapped with the button-and-joystick panel.
The back access door has a bottom-hinge which is a pair of 12-inch piano hinges.  Note the power button.  More on that later...
A window sash latch is used to keep the back access door closed.
The front access door is hinged on a pair of Euro hinges, so the door can be inset from the front of the side panels.

The PC inside the cabinet is powered on/off with a regular arcade button.  To do this, I cut male/female patch panel wire in half, and soldered both halves to a single wire.  The other end of the wire has a connector for the arcade button.  The patch panel wires plug directly into the motherboard/case connections for the PC's power button.  This allows me to power on the PC with the button on the back of the cabinet, or the PC case's power button.
The sideart is printed on black self-adhesive vinyl from Souldraw.com. I used this guide to install the art. 
A shot of the final product in action...

A fair amount of effort went into the control panel.  I tested several mock layouts on paper until I found one that I liked.  Slagcoin.com is basically the online bible of arcade button layouts, and I made full use of it.

I started by cutting out the six sides of the control panel box, and attaching furring strips to keep them together.  I screwed and glued the strips on, screwing through the MDF and into the furring strips (since the wood of the furring strip will do a better job gripping the threads at the end of the screw than the MDF).

Arcade control panel side boards.
Then I glued & screwed all the pieces together.  The top is not attached, since it will be detachable on the finished product.  And the back panel also isn't actually screwed on for now, because I need to be able to access the underside of the top panel to formulate some kind of latching system. (Ultimately, I never actually made a latching system, and the control panel simply rests snugly in place.  Having the back panel detached did help immensely with the wiring process, however.)

Arcade control panel box assembled.
The next step is to prep the top panel for joysticks and buttons.  I printed a full size version of my control panel graphics, and clamped them to the top piece.

Graphic template clamped to control panel top piece.
Then I center punched all of the holes.  I want these holes to be drilled as accurately as possible, so I'm taking my time.

Center punching button holes.
With the holes center punched, I removed the graphic template, and used a small drillbit to drill pilot holes.

Button and joystick holes pilot drilled.
Now to drill the holes for the buttons and joysticks using a 1-1/8" forstner bit.  I started with one of the joystick holes, since any mistakes will be covered up by the joystick washer.  After drilling a couple holes, I noticed that the bit was tearing chunks out of the underside as the bit came through the MDF.  So, I started drilling about 1/4 of the way through the bottom first, then flipping the board over and drilling through the top.  This seemed to go more smoothly.

For the joystick attachment, I needed to rout out part of the underside for the joystick mounting plate, because un-routed 3/4" MDF would only leave a tiny nub of joystick sticking out. First, I drew a square that matched the size of the joystick's mounting plate, centered on the joystick pilot hole I'd drilled.  I actually marked out the area I needed to rout BEFORE I drilled the 1-1/8" holes (and after I'd drilled the pilot holes).  This is because it's a lot easier to find the center of a tiny drilled hole than a 1-1/8" hole.  Then I simply routed out the area inside the square that I drew.  You can either do this with a fancy template, or you can just do it by hand (since nobody will see the underside of your control panel anyways).

1/4" deep joystick inset routed on underside of control panel

Unfortunately, because I didn't drill my pilot holes with drill press, where they exited on the underside was just slightly off-center from the intended locations.  Luckily, it wasn't enough to be noticeable up against the art.

Test fitting joystick and buttons on cutting template
Once everything is drilled, I filed the front two corners so they were rounded, and then used my router to create a T-molding slot around the front & side edges of the control panel (more details on how to do this in the "Putting It All Together" post that's coming up), and primed/painted the control panel black.

My control panel art was ordered from GameOnGraphix, along with my admin panel art.  I created my own art in GIMP, and used their custom design service. [Click here to download the GIMP art file for my control panel] The polycarbonate-coated material they use is terrific for this application, and it was easy to apply.  The art is basically a big sticker. Peel off the back, and stick it to the control panel.  I lined up the holes from the underside by shining a light through the art to make sure everything was in place.  It was slightly off-center when I first started to applied it, but I was able to peel it up and reapply it with no problems.

Lining up the control panel art
Once the art was applied, I used a sharp X-Acto knife to cut around the edges and inside the button/joystick holes.

Cutting the control panel button holes

Control panel art applied and fully cut to fit
On the underside, I carefully aligned the joysticks where I wanted them to be, and marked where the screw holes needed to be placed.  Then I drilled my 0.4" deep holes (carefully, because the wood is only 0.5" inch thick here) and inserted EZ-Loks to secure the joysticks.

Joystick EZ-Loks
Now to attach all of the buttons and joysticks permanently.  My buttons and joysticks were all bought from GroovyGameGear. The buttons are Arcade PRIME buttons.  I splurged on "premium" micro-switches for the main 8 buttons for each player (GGG no longer sells the "premium" switches, it appears), but they were louder than the standard switches.  So, I kind of wish I'd stuck with all standard switches.  Leaf switches would've been quieter yet.  The joysticks are OMNI2 joysticks which can be switched between 4-way (old games like Pacman only had up/down/left/right movement) and 8-way mode.  Because essentially any game with a second joystick was an 8-way game, player two's joystick is permanently in 8-way mode (I contacted GGG and they gave me a $10 discount to get it this way).

The joysticks are screwed into place with screws and EZ-Loks.  The buttons are simply hand-tightened using the nuts that come with them (I bought a fancy nut-tightening tool for the buttons, but it was totally unnecessary).

Button and joysticks secured
The wiring isn't particularly difficult, but it was tedious and very time-consuming.  All of my controls interface with the computer running the arcade cabinet using an IPAC-2.  You can either buy these directly from Ultimarc; or in my case through FocusAttack, which saved quite a bit of money on shipping.  You could also try one of GGG's encoders, the cheaper Xin-Mo encoder (found commonly on eBay), or one of the much cheaper (but much more complicated to set up) Arduino Leonardo boards.
Ultimarc IPAC-2 Encoder Board
My control panel is actually detachable, so I needed to be able to easily plug/unplug all of the wiring.  I did this by wiring everything through M/F parallel cables (one for each player).  I cut the cable in half and wired the individual wires from one end into the buttons, and the corresponding-colored wires from the other end into the IPAC.  Then I plug it all in by connecting the male and female ends of the cable.

Control panel wiring for player one

Unfortunately, the wires inside the parallel cables are ridiculously thin, so I needed to solder a short length of thicker 22AWG wire to each wire so I could hook it up to the IPAC's screw terminals and into the quick disconnects attached to the buttons/joysticks.

Parallel cable wire soldered to 22AWG wire (note the extra piece of shrink tubing on the thinner wire so the main shrink tubing had something thick enough to grab onto on that side)
At this point, all I needed to do was attach the T-molding (again, more detail on this in the next post; and you can see the T-molding applied in the photo at the very top of this post).  I thought I'd need magnets or a latch to keep the control panel in place, but it was clear that I didn't need any of this once I got everything assembled.

The marquee serves no real functional purpose except to look really freakin' cool.  Building this part wasn't exactly rocket surgery (although I had a couple struggles).

Basically, I needed a ceiling and a floor for the marquee.  These are just strips of MDF held in place by metal L-brackets (if I'd used little blocks of wood to attach them, there'd be dead spots on the marquee where light couldn't shine through the wood).  Then I added some scrap wood to the back of the marquee area where I'd mount the backlight.

Marquee Construction
I ordered my marquee artwork, along with the side panel and keyboard surface art, from Souldraw.  The marquee art is printed on Backlit PVC Film.  My art had some scuffing and air bubbles, but for the price, I'm happy with what I got from Souldraw.  I had the art printed with about an inch of buffer space around all 4 edges, so I could cut it to size and not worry about it being too small.

Marquee art, full side panel art, and keyboard panel art: $88.46 shipped from Souldraw.com
The marquee art is simply sandwiched between two pieces of Plexiglas.  I left the protective film on the piece of Plexiglass behind the art, since it helped to diffuse the light somewhat.

You can buy specialized arcade marquee brackets to hold the art in place, but they tend to be somewhat overpriced.  I used clear plastic corner guards that I picked up from Home Depot for about 8 bucks.

Plastic Corner Guard
These brackets have little dimples dispersed across them to help nail them onto walls, so I had to cut the brackets in such a way that no dimples would show up on the front surfaces.  There are a couple dimples on the top & bottom, but they're totally not noticeable.

With the corner guards cut to size, I clamped them into place with the art/plexiglass in position.  Then I drilled three small-diameter pilot holes through the top and bottom surfaces.  Using these holes as guides, I added EZ-Loks to the cabinet (I love these things!).  Then I widened & slightly countersunk the holes on the brackets so I could screw machines screws into them (much like I did with the wooden ruler on the monitor glass retainer).

Next, I painted the inside surface of the brackets with black spraypaint, and then covered the dried paint with tape to protect it from scratching.  This gave the brackets a nice, glossy, black finish.

Now I needed to light my marquee.  

The LED Tape I Eventually Found to Light My Marquee
First I tried a fluorescent light fixture, but it was too big for the space I'd left.  Then I tried LED tape powered by an AC adapter, but every adapter I tried caused electrical interference with the sound system in my cabinet.  I eventually found USB-powered LED tape that worked great.  Also, since it's USB-powered, it automatically turns on and off with the PC powering my arcade machine.

Completed Marquee (Note the Flaw on the Lower-Right Corner)
The screen area is made primarily of 1/2" MDF, with several trim pieces to keep a glass panel in place.

I started by taping several pieces of paper to cover the entire screen-area on my monitor.  This gave me a template to cut the hole for the monitor in the MDF (below isn't my actual monitor, but it shows the general idea of what I did).  After cutting the hole, I used my router to put a nice, rounded bevel on the cutout.

Cutting Stencil for Screen Cutout

For the top edge, I attached a strip of 1/2" MDF. I previously routed 1/4" off the area where the glass would rest.  

Top Edge of Screen Panel

For the bottom, I have a similar 1/2" MDF strip routed to 1/4" for the glass to rest in.  I also added an additional trim piece which matches the bottom trim piece on the admin panel. This trim piece also serves to create a slot for the monitor glass to rest in.  On both sides, I glued a 1/4" thick strip of MDF, so the glass can rest securely on all 4 edges.

Bottom Edge of Screen Panel

On the back, I attached two pieces of scrap wood that help to position the monitor.  I drilled holes in these strips, and inserted some EZ-Loks which will hold plastic hangar straps to keep the monitor in place.
Screen Panel: Back Retainers

To keep the monitor glass secured, I used a cheap wooden ruler.  I sanded all of the markings and indentations off with my power sander.  Then I drilled & countersunk 3 holes to secure it to the cabinet.  To compensate for the angle of the speaker panel above the screen, I filed the back-top edge off from the strip so it could rest snugly against the speaker panel above it.  When everything fit the way I wanted, I painted it black to match the rest of the cabinet.

On the screen cutout, I drilled holes matching those of the wooden retainer strip I just created.  EZ-Loks and machine screws hold it in place.

Screen Panel Completed

I just realized that I've been seriously negligent on my arcade cabinet updates.  I actually finished it a few months ago!

Next up: The speaker panel.

First off, I created a template on 1/4" MDF to help me rout out the speaker holes.  The old butter dish gave me a round stencil for the cutout.

Measure twice; cut once.  Because I always measure incorrectly the first time.
Then I used this template to route out the speaker holes (and patched up the spots where the cruddy 40-year-old router I was using mucked up the panel).  I glued scrap MDF and furring strips to the back in order to keep the speakers properly aligned.

Speaker panel cut out with speaker guides attached
As you can see below, once the cabinet was assembled, I then used EZ-Loks & screws to screw some plastic hanger straps into the furring strips to keep the speakers secured.

Speakers secured in place.
On the front, rather than having some off-the-shelf computer speakers showing through the poorly cut holes, I wanted to give the speaker grill a more professional look.  I started by cutting a piece of 1/4" MDF to the size of the speaker cover I wanted, and then I cut holes for the speakers and the dials.

Speaker cover dimensions laid out on speaker panel and cut to size.
To keep the cover in place, I ordered some Parts Express grill guides off Amazon.

Parts Express Pressfit Speaker Grill Guides

With the cover still clamped as shown above, I drilled through both the cover and the speaker panel with a small-diameter drill bit.  This would ensure that the grill guides would line up correctly when I installed them.  I widened the holes to 7/32" on the speaker cover, and 11/32" on the speaker panel.  It takes a LOT of force to get these guides into the holes.  (Note: I recommend hammering these into place before you completely assemble the cab.  In my case, I waited until the cab was nearly completed.  When I hammered the female guides into the speaker panel, I ended up partially ruining the bondo patch I'd made in the joint between the speaker panel and the marquee panel.)

Then I primed & painted the cover black, and covered it using speaker fabric and spray glue from Parts Express.

To do so, I cut the fabric to size so it would wrap completely around the front and back (with the overlapping seam on the back, not passing through any of the holes in the cover). I sprayed the glue onto the back surface of the cover only, let it dry for a few minutes, and then wrapped the cover with the speaker cloth.  I cut the speaker cloth inside the hole for the dials, and wrapped it in a way that the cloth would adhered to the glue.  Then I hammered the grill guides into place, so they would also help keep the cloth tacked down on the back.

Speaker cover completed and installed
With the cover completed, I just pressed it into place on the cab, where I had already hammered-in the female speaker pins.