Actually, Etsy allows the sale of three categories of items: handmade, crafting supplies, and vintage. Obviously, nothing from Shapeways is going to qualify as vintage, but you could sell items from Shapeways if they are to be used as crafting supplies (e.g. buttons, possibly), even without additional finishing. (However, from "The DOs and DON'Ts of Etsy": "A third-party vendor may not fulfill your orders to your Etsy customers on your behalf (no drop-shipping).")
For handmade objects, Etsy states that "production assistance for certain intermediary tasks in some crafts may be acceptable." However, they add that "an assistant or third-party vendor's involvement may not comprise a majority share of a handmade item's creation." It seems unlikely that an item from Shapeways that has merely been polished or finished really meets this condition, but I know that Nervous System have been selling their rings on Etsy, and they apparently haven't had any difficulties yet.
(If Etsy does decide that you are listing something inappropriate, you forfeit your listing fee for the item, but I don't think the listing fees are very high.)
Last edited: Oct 14, 2010