This spool is made to be able to quickly change plastic of different colors which are on rolls of different diameters. Each hook is easily adjustable with a single bolt in a captive nut. It is important that the spool does not turn too easily which would allow the filament to get tangled.
The arms of the spool are aluminium extrusions of 10x10 mm.

The idea for the construction is borrowed from the "damped spool" by FatFreddie.

Cut 3 pieces of about 22 cm of 10x10 aluminium extrusion. Fix the arms with small bolts to the center piece. In my case the center piece fitted so tight, I had to use a heating gun to help and there was no need for bolts. Use 25 mm M3 bolts and nuts in the hooks at the end of the arms.

I designed this using 123d designer; the design files are included if you want to make any changes.