Just a knob with an inlaid magnet to store the Build Plate Cleaner by @kstudioca_1569715 against a metallic wall or the printer enclosure.
Neodym magnet: ø10x5 mm
Update 20240401:
Increased tolerance settings for the thread (Knob_h25_magnet_v4.stl)
Update 20240402:
Added a 40mm version (Knob_h40_magnet v2)
The author marked this model as their own original creation.