hi jigenjuke, it sounds like we're working on similar projects. I'm building a bunch of 1:4 mini cabs and had some of the same questions you do. For the sides, control panel, marquee etc I used adhesive vinyl decals on top of color matched paint and was pleased with the results, but I might top it with varnish or something to smooth it out and make sure they don't peel. For the buttons I was going to mold and cast my own, but settled on buying some small ones that look nice and have good action. They're about 1:2 scale so it kinda throws the proportions out of wack, but they look good on the control panel and are very playable. If yours end up being about 1/8" they should be comfortable to use, thats 1:6 scale right? Are you casting an entire assembly similar to a regular arcade button? For the coin door, I modeled and printed it on a 3d printer then made a mold of that, but I couldn't make lit/working coin return buttons, definitely next on the list. Casting your own t-molding is pretty hardcore. I had two options: custom order 9,000 feet of 1/4" t-molding, or buy a couple rolls of 1/4" colored vinyl tape. I went with the tape. Color me green with envy over $50 Pico-ITX boards.. thats a steal at twice the price! Do you know how well they run mame?
Having made a blue DK, I'd vote for the red one.. it stands out more and really pops.