So I'm not a huge fan of excess support material and excess material in general. I designed this spool holder to only require supports on the threaded sections (As long as your printer can handle a 6mm bridge).

The outer cylinder diameter is 51.5mm. This should hold most spools from my experience. All the parts came out to approx. 70g of filament. 

A standard 608 bearing can be mounted on either side but it can be used without them as well. 

Relevant Print Settings:

• I used a 0.6mm to print this but a 0.4mm nozzle would also be just fine. 
• Layer Height: 0.3mm with variable height (~0.2mm) on the threaded sections. 
• Material: PETG 
  • PLA would likely be fine as long as it won't be exposed to heat. 

Note: 

• In the “Spool Holder All Parts.3mf” I have painted supports on those sections. Some printers may print threads without need for supports. I didn't want to spend the time tuning to get it perfect. 
• The bearing shaft is press fit. Depending on your print settings you may need to glue it in or sand it slightly to get it to fit.