This is what my non-too-glamorous drum roasting setup looks like circa 2004. The drum very comfortably roasts 3 lbs and could probably do as much as 4 lb or as little as one. Basically, you just get your grill to a different starting temperature (note the dial thermometer inserted in).

I roasted 4 lbs (12 cups) of cocoa tonight. I really need to get my drum roaster finished. I think it will give a much better end product. This batch was done in the oven, distributed between two shallow dishes. I preheated to 425 F and put the beans in.