Improved SpoolHolder with Rims

I took Henry's great V2 Spool Holder for the Prusa Drybox and added rims and a longer cylinder to it. This ensures that the filament spool cannot glide off the sides and stay nice and centered. You have to use the stands from the original file for this holder.It only requires 2x 608 bearings instead of 4 and helps filament spools roll more smoothly.