Since most of the filament I purchase comes on cardboard spools I've tried several printable spools and adapters but each one had different quarks that I just wasn't super satisfied with one of the biggest being the size and space that they take up when not in use. This prompted me to design my own. This spool is designed to split into 5 pieces for more compact storage, while being easy to print and assemble.

To avoid the need for support materials I recommend printing the Core Thread and Body together the tolerance gap I've used will ensure it prints nicely but comes apart fairly easily once printed.

Edit: 4/17 uploaded v2 with reinforced storage cavity and closed up the gap inside the assembled core. Updated the print profile to use random seam to help prevent spools from getting stuck in the AMS. 

Use the built-in cavity to secure the loose end of your filament.