I used a West Bend Air Crazy popcorn popper that I grabbed from a Target down the street.
First batch was roasted on my work bench in the garage at 34 degrees F ambient temp and 38% humidity.
Roasted to just about 30 seconds past "first crack" (at exactly 4 minutes in) where the beans snap as they pop along their seam (the roast process has two distinct cracks depending on how long you roast).
Turned out pretty good. Fairly light roast which I like, but my gf doesn't. Next batch I'm going to attempt to go past second crack to get a really dark roast for her, but that will involve taking the popper apart and removing the thermostat and possibly the fuse as it currently regulates the internal temp and prevents to from getting hot enough to go to second crack in the proper amount of time, if at all.
The popper roasts about 1/2 cup at a time in 5-10 minutes, which is enough for about 3 cups of joe. The smell is amazing, but the roast process kicks out a ton of smoke and chaff which does not smell amazing. Definitely a good project for the porch or garage.
Edit Bean = Ethiopian Limu