First off I don't recommend paper mache. That was the biggest fail I think I have had to date (I wish I did have pictures to show how bad it actually was). So after several attempts at that we moved on to clay. His teacher was very clear that we shouldn't be spending a ton of money. Which I'm all for! So we made the clay from scratch! This is pretty simple.
1 cup salt
1 cup flour
1 cup water
You mix it over low heat until it hardens to the consistancy of playdoh. You then set it aside to cool. Make sure it has completely cooled because you wont be able to handle it/ work with it very well.
Next you need to find something that is about the right shape as a volcano and that would fit over a water bottle of 16oz. I went searching through the kitchen and found a popcorn container!
After many failed attempts his project was complete! And the running total was just under 4 dollars! I forgot to mention that the 16 oz water bottle was giving to each student. It didn't just appear out of nowhere lol.
I hope it helps some frantic mom out there the next time their child comes home and explains that they need a volcano. Trust me my mouth was on the floor thinking that this teacher has lost her marbles and that I could never get it made.