A side-mounted spool holder for the Ender 3 v2. Will most likely also fit the original Ender 3 and 3 Pro as it just needs the 40x40 extrusion behind the left of the machine to support it. This holds the spool directly left of the extruder inlet giving a more direct path, and removing the weight from the top of the gantry to increase stability.

06 Mar 2021 Update - v2.3 increases the slot sizes for the t-nuts from 4.2mm to 5.2mm. This should solve the problems some have had with fitment. The alternative rear-mounted design already has the 5.2mm slots and seems to be ok.