Full attribution to alobal https://www.printables.com/model/727127-bambu-a1-ams-lite-prusament-adapter

This allows a Prusament spool to be installed onto an AMS lite. The indentations on the shaft go between the spool claws, allowing the projections on the shaft base to sit over the spool claws. Then the large nut is threaded over the shaft to lock the spool in place.

To install, put the shaft inside the spool first. The large threads may catch against the inside of the spool as it gets pushed through, just squeeze them in a bit to get it to clear. Put the spool with shaft onto the AMS lite spool holder with the projections over the spool claws. Push it flush, then thread the nut onto the exposed end of the shaft.

It works very well!

If you're slicing this yourself, it needs to be made strong, particularly if you're printing this in PLA. The designer advises that you use 5-6 walls. I did, and I also used 50% gyroid infill, although that's not as important because there's not much infill here. You will need the shaft to be strong, otherwise its segments will crack as they flex. I printed in 0.2mm layers. 0.24mm or 0.28mm layers might increase strength and reduce print time but could adversely affect the screw threads.

The designer advises printing this in PETG, which would make it even stronger, but it'll work in PLA provided you print it with lots of walls.

EDIT: I found it also works on MatterHackers clear spools with a 51mm ID. These spools are a bit narrower so the original nut bottoms out before it grips the spool. The designer was nice enough to make a deeper nut which grips this spool perfectly, just make sure to install the shaft and nut on the spool first, then push the spool onto the AMS lite spool holder. I've included their revised design and I'll put it as a new print profile. I printed it in (purple!) Bambu Lab PETG.