Printing out spools is expensive. Cutting them out of MDF is cheap.
The spools are 160mm in diameter and 90mm in width. Each spool requires two ends and two plates cut out of 3mm MDF and glued together.
The easiest way is to print out the PDFs, double-check the scaling is 1:1, glue onto the MDF and cut out using a scroll saw. I suppose laser cutting can also be used.
Drill some 2.5mm holds in one plate to attach the start and end of the filament (see the picture).
Each spool easily holds 100m of 1.75mm PLA.
No DXFs are available as the DXF export from Alibre Design seems to have problems.