ointment mills essentially flatten the cream over and over.. mortar pestle sounds good but also a scraper on glass that you can work back and forth alot and clean up easily.
stay away from natural stone mortar, ceramic non porous is what u want.
also, we used to get syringe attachments that you could squirt back and forth a bunch of times, but that may of been for making of the PLO itself, but I think we dissolved contents prior to mixing, cant remember.. anyway, id be interested to see absorption of alcohol vs PLO, one would think PLO would work better and perhaps a bit longer absorption, but thats a guess.