SmartRap X and Y motor fishing line spool

For those of you who have D-shaped stepper motor shafts here's a rough attempt to resolve this issue (I have this problem too). The little holes on the outer flanges allow you to thread your line so that when you wind it, there is no slip. 3 to 4 windings should be more than enough. I will try to print this and see how it works. I have a hole and slot for a 2.5mm grub/set screw and nut as well. I have no idea how this will affect accuracy but the working diameter of the spool is 10mm, so I