Herb grinder that grinds to a fine dust. The design keeps the bearing face separate from where the herb is ground - all plastic-on-plastic friction occurs around the outside, and the gaps around the bearing face allow any residue to escape harmlessly.
Regardless, for safety, I would suggest only using PLA here, due to its non-toxicity.
The very first one these I printed is still working fine, 9 months later, after regular use.
I'd also recommend ensuring your retraction settings are well tuned, as the teeth require very frequent retractions.