At the cost of dimensional accuracy. Anything abrasive enough to polish the flats is going to take material off all the corners too. This is a sub-optimal solution, IMO at least... SLA gives you prints that look like they've come out of a mold. You really can't hope for anything much better. The resins are the weak point, though. But like I said, I've seen incremental improvements in printed resin strengths over the last couple of years. If they continue on the current "glide slope" they'll be competing with ABS soon and exceeding that eventually. One of the new resins I'm experimenting with produces a print that is kind of like a cross between Nylon and Acrylic. It's fairly flexible to a point and then it snaps like glass. My only problem with it is that it's a little too soft.