I'm looking for a company where I can buy pestles or potter sticks to crush samples in microcentrifuge tubes/pcr tubes. I can only fing potter sticks for 1.5 mL tubes.
You can make your own by putting glue in 0.2 ml tubes and using a paper clip stuck in as a handle. Once set you can then use this to grind your sample.
The other way is to gently melt the end of a pipette tip, and then stick it into a 0.2 ml tube to shape it. I've not tried this method, but I think this would be the best of the two alternatives in this answer.