Remember when I said I had to stop myself from posting anything that comes across khymos.org and Ideas in Food? Apparently Make is one of those, as well, at least for their food related posts.* However, in this case, a casual exchange on twitter prompts this one.
At the time, I just forwarded a link to an old engadget article about seriously modding a popcorn popper. It's a good read, but then I ran across this article on Make about an airpopper coffee roaster, with included video, and it is so much easier. No modding, available inexpensively though yard sales or eBay. Go to it! You can pay for the popper with about 3lbs, based on the price estimates in the video. Plus, your coffee will taste better. Less money, better coffee. *- To be fair, I have scooped a few of the more mainstream sites with a couple of these, so I apparently have my finger on the heartbeat of the something something blah blah.