I used to use 3ds max, but I don't want to have to download the trial for this small project.

I'm trying to build a model of a couch/bunkbed that I'm planning on building. It's all made of 2x4s or plywood. Are there any 3d modeling programs that I can specify dimensions easily and "build" this thing in 3d, without having all the complex functions of 3dsmax? I just want to be able to make rectangular solids of the right dimensions, and rotate/move them.

Any suggestions?