Maybe I'm solving a niche issue, but I have a 5 gal. 4 hp Craftsman stainless steel shop vacuum (model CMXEVXA18115) and it's impossible to find a replacement filter that actually fits. So I went to Lowe's and I found this filter (model CMXEVCVVCFSCM) that literally says on the box it's supposed to fit my model of vacuum, but I get it home and both the old filter cap and the new one that came with the filter don't hold it on. The old one had threads that are too short, and the new one had this dinky little t-shaped thing that's not wide enough to grip the internal threads.

These two models allow the bigger filter to fit onto the old threads. I also used the rubber gasket that came with the new filter in between the handle and the bottom of the cap, but you could probably leave it out and it would still function just fine.

I recommend printing in PETG or ABS. The photos show a PETG print with 0.10 layer height, 30% infill, and supports enabled, and all other stock settings for a MK4 with the Prusa PETG preset. YMMV.

If you have any suggestions, please let me know!