How to Pulverize Set Plaster for Re-use

I did this at TechShop Menlo Park. http://www.techshop.com

To save yourself a few dollars, you can re-use old plaster molds to make fresh plaster powder.

Dig for whatever you can use to wrap the old plaster chunks and prevent the dust you'll be creating from flying around.

Load your set plaster pieces into your cardboard or plastic sheets.

Wrap up plaster chunks into a nice secure wrap.

Anything big and heavy will work. I found a huge steal pipe and used it as a rolling pin.

Keep smashing as hard as you can. Watch your toes!

Open your package to find plaster dust with some chunks. You can repeat steps to get it to its original powder form but you must mix it with fresh plaster mixture for mold making anyways and so the chunkiness won't matter. 
This is a great way to get some anger out while simultaneously creating something useful and saving some money for your future art supplies.