Do us a favor and don't offer advice anymore. kthx.
you think the vibration is transferred to the amp via the supports connected to the box? no it's gonna be from the big ass surface area on the bottom of it catching the air waves. And.. how would he sandwich foam between 2 pieces of wood? spray glue? I wouldn't trust my amp to that. Putting screws through it all will defeat the purpose, coupling the top piece to the bottom piece with hard pieces of metal.
OP- figure out what subs you want, then figure out how much space you need, then figure your box out and mount the amp out of the way of the ports, you could do a recess in the front of the box for it if theres no where else to put it.