UPDATE: Added a Ver. 2.0 that drops the material cost down to 20.3g, making it (probably) printable with a filament sample.
An adapter to mount the A1 mini's included spool holder to the top-back of the printer. Strongly inspired by Iacopo's A1 Minimal Handle and Spool Holder, but I'm tweaking my own work on a vertical mount adapter - now with far fewer fillets to screw up and 18g less material.
Requires the included piece of plastic the spool holder clips to, and the two screws that normally attach that piece of plastic to the Z-axis (see pictures).