This sounds exactly like what I had in mind. It says you can carve directly in blocks cast from the material. The shrinkage, during sintering, is only 5%, too. One limitation I'm wondering about is the maximum height of 20". I wonder why that is?
They have an intro offer whereby you can order a free block of the material for carving, then send your carving back to them for sintering and they won't charge you for the process. Sounds like a sweet deal.
I'd like to find out if I can fire my own, though. According to another website, "Sintering temperatures can range anywhere between 1450-1550 degrees for bronze." An electric kiln can easily acheive such temperatures and so can a butane torch, so, it's entirely possible to fire your own bronzes. A little experimentation with mixtures of wax and bronze powder can probably duplicate their product, also. It would be cheaper to do so, not to mention faster (there is a 4 week turnaround time using their services).