Searching "sleeve*" on BrickLink brings up a pretty useful list of dual-molded arms: http://www.bricklink.com/catalogList.asp?catID=20&catXrefLevel=0&catType=P&q=sleeve*&catLike=W There's no easy way to look for dual-molded legs, on the other hand. They're generally not inventoried on BrickLink individually, and as assemblies they use the same terms like "boots" or "shorts" that are used for many printed legs assemblies. But searching for "boots" or "shorts" might at least help narrow things down. Unprinted dual-molded legs can be seen here. But printed ones have different design IDs for each print, so can't be browsed as easily in the Brickset database.