Prusa Mini Spool Holder

it is easy to assembly, you can look the image, expecially the one in CAD, to understand better where and how it works. It won't stress your Z axis and the spool arrives directly near the hole of the extruder. It works better if you will use a ptfe tube in the extruder entrance.
Print it in PETG or ABS-ASA. PETG would be perfectly fine except if you plan to use the mini in the enclosure for printing high temp material, in that scenario i suggest ABS or ASA (they works identical, ASA is a bit more "print friendly" then ABS; but well, this is up to you).