I'm looking at small-diameter random orbit sanders, which I would use to sand concave furniture parts -- like scooped-out chair seats, and sculpted back rails. I think my sanding problem is the same as a turner sanding the inside of a bowl, hence the post here. I don't have a big compressor, so I'm only considering electric sanders. I see three 3" random orbit sanders. Festool and Mirka have sanders in the $500 range. Metabo has one for a bit less than $150. Am I missing any other possibilities? Does anybody have experience with these small sanders?