I checked some of the links in the original article and found a few were dead.  In my efforts to find them at the homeroasters.org site, I encountered a couple new resources I recommend to you as you explore using a simple popcorn popper to roast coffee.

First , Homeroaster.org has developed several 'how-to' videos including one entitled Roasting Coffee at Home with an Air Popcorn Popper .  This is not a build video, but a how-to roast coffee beans using an air popcorn popper video.  It seems like a great complement to our build tutorial.  The reviewer points out a couple weaknesses in controlling speed and temperature of roasting that our build avoids in the finished, modified PopperyII.

I noticed, too, that Homeroasters.org has a forum topic devoted to popcorn popper roasters and roasting: Homeroasters.org » ALL ABOUT ROASTERS » Popcorn Popper roasting

I thought I'd mention these resources to help you jump-start your knowledge of simple coffee roasting.