2nd timer needs help/info please

Neat site! All kinds of info that I can definitely use. I used plaster of Paris and colored glass stones about 15 years ago on a wood table. Put the P of P on, and pressed in the stones After plaster of Paris was dry I put a coat of polyurethane over it. Looked good for about 6 months, then turned yellow. Have learned to read label for non yellowing polyurethane. That is the extent of my 'mosaicking".

I want to try to do a BB, a birdbath and a wooden birdhouse. My question is; can I use a tumbler from, oh heck, brain fade...can't remember the name...oh Harbor Freight. Anyway they have tumblers around $25. Can I use that to tumble both broken bottles, glasses etc and broken china plates, saucers, etc. Do I need to, or is it not advisable to tumble china?

Ah, so many things to do......so little time!

Thanks for any assistance you can give.