From: Kevin Kelly Cool Tools
I wanted to try roasting my own coffee but was reluctant to plunk down $100 just to try it. The solution: a hot-air popcorn popper. Sweet Maria’s web site has detailed instructions on how to use a popcorn popper to dry roast coffee beans. I already had a popper (a $3 “Presto” I got at a thrift store), so I ordered a pound of green beans. Turns out it’s very easy. No tinkering, hacking or rewiring necessary.