Repaired Sanding Disk Holder

The bottom wasn't flat so I repaired it to be better

"Inspired by gordyt47_9409's 5 inch sanding disk holder. But that one had such sturdy, thick walls, that it would have taken 330 grams of filament and over 16 hours to print. Naturally, I felt it expedient to stay up all night and remake it in OnShape, including learning how to parameterize it... you know, just in case anyone wants to use it with different preferences or purposes. All to reduce that to 129 grams of filament and 11 hours of printing - I think I saved $4, woot!