You can't build something like that in an apartment. I live in an apartment also. The complex wouldn't allow soundproofing a closet! Besides, have you seen the size of the closets in most apartment complexes? Here's what I do. I limit my practice sessions to no more than 45 minutes at a time, and I practice between the hours of 11:00 am and 7:00pm. I talked to my neighbor above me and my neighbor behind me. I asked them if they had any complaints and neither of them cared. The neighbor behind me said that he's only heard me play when he walked past my door, that the sound doesn't bother him at all. The neighbor above me is very tolerant. He works in a bar, so he said the noise doesn't bother him at all. One night I was working on some blues, playing around with my keyboard recording and sequencing some stuff. He said that it sounded really cool, and he had to come check it out. The guy said he used to play bass guitar, so I handed him my Fender Precision bass and asked him if he wanted to lay down a bass track for me. He thumped around on my bass for a few minutes, and put down a pretty modest buy "tasty" blues bass line. The point is, if you get to know your neighbors a little, they're apt to be more tolerant. Just try to be respectful, let them know that they can come to you if you're being too loud and you will quiet down. Of course, try to play soft...ok, yes I play a Conn 10M and trying to play SOFT with a 10M is like trying to drive a race car on ice! But, I TRY to be as quiet as possible. There's always mom and dad's basement if all else fails!