Spool Hub
thingiverse
I'm designing a custom centering disk, tailored specifically for my spool holder (https://www.thingiverse.com/thing:1743397), and you're welcome to create your own rod or use the hubs instead. These disks are made to fit perfectly into 56mm spools like mine from Tianse, and I'll be uploading a .sldprt file if anyone wants to modify them using Solidworks.
Download Model from thingiverse
With this file you will be able to print Spool Hub with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Spool Hub.