Baby's First CP

[sunspot]

Hi all, didn't have much luck searching the archives for this so please accept the pardon if I missed anything good.

I'm an older arcade-era guy, and would like to build a couple of small lap/sitting-on-couch-friendly CPs for my wife and I to play 4-way joystick games, because PS4 controllers, though great, suck for 4-way joystick games.
 
I bought a couple of Arduino Pro Micros and I was thinking about ordering a pair of Tornado Terry sticks.  The rest, I could use some good advice.

I have the Atari 2-player/trackball controller from Micro Center and I like it.  It's all I have to go on right now in-hand to use as a reference for DIY CP ideas.  3/4" plywood/MDF seems a bit of overkill for something this small.  Would 1/2" be ok instead?  Or should I consider aluminum, steel, or plastic?  Or maybe there's a large enough pre-fabbed project box for sale that would do the job nicely?

How many buttons do I need?  I believe 3 buttons+Coin+Start should be enough for any 4-way stick game?  What are the minimal interior dimensions required?  Are there any templates out there?

Lot of questions there, so thanks for any feedback.