The new design uses 3 layers of 18mm MDF, cut on a CNC router and securely glued together. The sheet metal will be the same and it still uses arcade sensors, just no other arcade parts.
To get a picture in your mind here's the first picture.
The second layer has holes for arrow wells, grooves for sensors, and small grooves for a |_| shaped bit to sit in over the sensors, like the L bracket on arcade machines.
The third layer consists of a full border and the 5 top panels. The 5th panel still has to be cut.
This method should make the pad very solid, and much cleaner than 2x4s & plywood.
This is the 3 layers glued together before clamping. Because it was cut by a computer controlled router everything fits perfectly, it's a bit pricey but damn it's wicked. One option I had was to make the square panels (minus the controller cover) part of the border, it would be easier and give a much smoother surface. I opted to make them all separate because the panel covering the controller has to have screws, and I'd prefer all the panels looked the same.
You can also see the ends of the wiring grooves on the bottom layer.
The next step once it's dried is to cover the sucker in sheet metal.
Because I need to do some long bends and want a perfect finish I was toying with the idea of getting is professionally bent. There's a guy who will do it fairly cheap, but it's still likely to be $100-$200. I figured this pad is for me so I'm not to worried about a perfect finish, I can always get it properly bent if people wish to pay for a pad with a higher price tag. I plan on getting ~0.5mm stainless steel and bending it using whatever methods I can devise.
I've ordered an I-PAC to use for usb input, it's practically made for this so I'm confident it'll work well. Failing that though, or for a cheaper option, I may look into creating an input board using an Arduino.
I will hopefully be adding the sheet metal by the weekend, I'll update once more progress has been achieved.