We run a couple of scripts to do this - one scheduled which runs hourly and picks up new demand for small volumes of builds from new orders, and a map/reduce for large batches of stock where we get thousands to build at once. It's not difficult to do but, as Sandii says, I'd recommend looking at your case for doing this before doing something similar. The build process works without any real issues, but the problem is the data usage that goes with it. Each build is a work order plus an assembly build record. If you move assembly items in volume, data usage quickly becomes an issue.