This is a tool to aid your use in finding the correct size center adapter for my FlexFit spool that I have posted. Rather than printing out full size center adapters only to determine that you may have measured wrong, I have created miniture versions so you can save on filament and time. Simply print out these mini adapters and test fit them into the center of your cardboard spool (after you have ripped one side off) and then you can determine which size you will need to print within my spool version.

These are simply for test sizing purposes only to save on filament and time. They are only 7.5mm tall.