I used a real cabinet building my MAME machine mostly because it was cheaper ($61 from eBay). I did read the Manifesto before I started, and I'm glad I did...
My cabinet was originally a Super Contra. It had been converted into a Tekken 2 machine by the time I got my hands on it, with who knows how many conversions in the middle.
The conversion was not done cleanly. The marquee (gone by the time I got it) had been held in place by Plexiglas screwed into the T-molding. The control panel had its original overlay stripped and a laminated piece of a Tekken 2 poster used in its place, and new holes drilled for the extra buttons for Tekken 2. All of the original art had been removed and painted over in black with a paint roller. The original speaker panel had been replaced with a new piece of fiberboard with two square holes cut out for the speakers, so the speakers (two car speakers added after the conversion) didn't fit right.
When I received it, the cabinet had its coin door, the Tekken-ified control panel (with two joysticks and 14 buttons), a power supply (not the original), a wiring harness (also not original), the flourescent lamp for the marquee, the glass, and the coin door (no mechs). No actual electronics, monitor, art, or marquee were present.
I replaced the control panel and drilled one small hole underneath the control panel overhang to add a volume control. I also sanded off the rolled-on black, re-primed the cabinet, and repainted with black and added starfield and purple nebula art. These were the only external modifications to the cabinet. Everything that was in the cabinet was reused except for the old control panel wood and the power supply.
I like to think that I've given this cabinet a new life: MAMEing it rather than maiming it. If there would have been any original art, I certainly would have preserved it. As it was, post-conversion, it really was more like "just a wooden cabinet" rather than a recognizable Super Contra. I have, however, tried to avoid modifying it any more than necessary for my needs.
So have I given it new life, or destroyed a classic? You can see it in the state I received it and in its new life at
http://mywebpages.comcast.net/celamantia/mamecab/ .