A quick search via Google will give you many MANY hits on people building their own cab. Be it MAME or JAMMA, there are a lot of people who have been there done that and put up some paragraphs and photos to show. The best site I came across for cab plans was Jakobud.
Jakobud has a lot of cab plans, especially for older style arcade machines. They have cab plans for Donkey Kong, Centipede, Q*Bert, Mortal Kombat, Tempest and many more. Each set of plans is in two images, showing side on and front dimensions. They also cover both upright and cocktail cabs. There is also a section for a nice MAME cab if that’s what you are after.
After looking through various plans, I have settled on the Centipede cab. I will be building a slightly modified version of it, as the control panel will be different, and I plan to build a lot of it into the front panel where the coin mech is. With everything built into a front door, it will allow me easy access to everything for maintenance, fixing and upgrading.
Here are the original centipede plans: