Thanks neuromancer, hyiu and rampy for the help, I'll be considering all of your alternatives, especially the piano hinge/clamp for the CP top. But I got a little scared about using clamps too to fix the entire CP to the cabinet.
What I thought: as I will not take the CP out every time (in fact, after I move the finished cabinet to my room and fix the CP, it will be removed only if I have to move to another house (not likely), I'm about to cut two pieces of wood to make the CP base that will be glued together: one in a "U" shape to incase on the cabinet, and the other one over to be the "true" CP base, and fix them with 4 "L" brackets inside the cabinet (I will have easy access because the coin door piece of wood will be really a door).
Some sketches (don't mind the text in Portuguese and the metric-like measures):
http://www.nightcap.hpg.com.br/sketch1.jpgAs you can see, the "U" shape wood is slightly wider and longer (around 30" x 13") than the other one that will be over (1 1/2" smaller, both wide and long), because I intend to do something like in this another sketch (now English-friendly

):
http://www.nightcap.hpg.com.br/sketch2.jpgIt will be the same for the 4 sides.
What do you think? I guess even Superman and Hulk would play NBA Jam together without destroying the CP.
