@kepstin @Rackuur @babe material also has implications here, in that some plastics hold up better than others in this application. inexpensive keycaps are usually made in ABS, which quickly shows mechanical and chemical wear; "premium" keyboards and aftermarket keycap sets often use PBT instead, which is costlier but relatively impervious

it's been ages since i used a model M and i no longer have one to check for material markings, but given they were built to a service life rather than a cost, PBT keycaps would be no surprise. certainly they're not ABS, which in a daily driver keyboard for me lasts maybe a year or two; none of my model Ms ever showed any keycap wear, despite heavy use both before and during their time with me