I have personally setup multiple arcade machines with a plexi bezel using similar process to that listed here. These are the steps I used
1) Purchase Plexi at LOWES, they cut it FOR FREE to any size, so use their service
2) Take it home, measure out the dimensions
3) Use Masking tape (Frog or blue) to line the edge of the part you want to have be clear (Taping on the INSIDE EDGE) use exacto knife GENTLY to make the perfect edge
4) Use this opportunity to place the bezel in the cab and make any adjustments, redo the tape as necessary
5) Cut a Piece of thin cardboard or thick paper to the size of the hole (Doesnt have to be exact) and tape this inside the part you want to remain clear) so you dont have to waste tons of tape
6) Make sure all the edges are taped snugly
7) Use a little electric hand sander with very fine grit sandpaper and sand the area you are going to paint, you just want it foggy looking
8)Make sure you let up the pressure while sanding near the tape so you don't sand through it
9)wipe it clean with rubbing alcohol 2 times
10) Spray with black flat spray paint
11) before it dries hold it up to a light and look for any light spots and touch those up
12) remove the tape and cardboard mask before the paint dries so that the edge doesnt get torn up
13) If you have jagged edges from bleed use an exacto knife GENTLY to cut the paint and clean the edges
I have done this on 4 different cabs with great results. looks super pro.