Reddit mentions of CMT 537.300.31 Forstner Bit, 30mm (1-3/16-Inch) Diameter, 8mm Shank

Here is a shopping list for people who want to do this kind of modification. It is fairly cheap to do, to be honest. Aside from the sanwa buttons, all of this stuff you can get at a local home improvement store for next to nothing. I spent a grand total of 30 bucks on this project. I recommend it for anyone who already has a sanwa arcade stick. If you're starting with nothing, just buy it from hitboxarcade.com since it will be cheaper. They charge 160 for the final stick.

(required)

• Four new 30mm buttons (OBSF-30): http://www.lizardlick.com/Sanwa-Pushbuttons_c_152.html
  
• Crimp Connectors: http://www.lizardlick.com/Crimp-Connectors_c_203.html
  
• Black wire (2 ft): http://www.lizardlick.com/LL-22-AWG-Stranded-Wire-Black_p_121.html
  
  (optional)
  
  
• Fat 40mm "jump" button (OBSF-40/40RG): http://www.gremlinsolutions.co.uk/products/OBSF-40.htm
  
• Clear buttons (OBSF-30): http://www.arcadeshock.com/items/sanwa-parts~buttons-balltops-gates-/list0.htm
  
• Plexiglass: http://www.professionalplastics.com/cgi-bin/pp.pl?pgm=co_disp&func=displ&prrfnbr=100409
  
• Plexi cutter: http://www.sears.com/shc/s/p_10153_12605_SPM2675756802P
  
• 30mm drill bit: http://www.amazon.com/CMT-537-300-31-30mm-Forstner-Bit/dp/B000P4LLFY
  
• 40mm Drill Bit: http://www.amazon.com/CMT-537-400-31-Forstner-Cutting-Diameter/dp/B000P4NO0E
  
• New faceplate art PRINT: http://photo.walgreens.com/walgreens/photo-gifts/product=posters

it's actually the exact size used for HAPP or IL buttons, for sanwa its actually 1 3/16 inch, or this one on amazon: https://www.amazon.com/CMT-537-300-31-30mm-Forstner-Bit/dp/B000P4LLFY/ref=sr_1_1?ie=UTF8&s=hi&qid=1282035499&sr=8-1
I had hell trying to get it right for ages since I don't have access to metric hole saws, and, to be honest, a Forstner bit works better, slow and straight and steady works best, a paddle bit can sometimes rip the wood, the Forstner bit will not.