I'm currently offering to build prop models--Half-Life, Milkshape--for anyone who wants them, so I can force myself to gain some experience with it.
I'm not so much disillusioned with mapping, as I always enjoy so much more building props for the maps.
One good way to let me know the exact proportions of what you want is to build the prop in hammer first, and then i'll use snapshots from the 2d views as the background in milkshape. After scaling, the proportions turn out to be perfect
Eventually when I get Source installed again, I'll start up with XSI and do the same.
Please PM requests, and perhaps I will post screens of the finished product(s) in this thread.