platform, for free 3d custom parts

hi, i look for a volunteer, to make a place where users submit hand sketches or 2d, and other users make 3d custom parts, or a portion of it. for free.
if it exist please tell me if not, or you want one other. please apply. I tought phpbb or a platform please suggest it.

three volunteers is good :
platform
getting users
moderating,

thanks,