>> maybe some rebar rods welded on the inside to each end
My guess is that 2, 3 or 4 angle-iron baffles bolted or welded to the sides would enough to make the compost tumble instead of slide when you kick the can. Even 1.5 or 2 inches projecting into the compost ought to be enough.
You might get more longitudinal mixing action with multiple, short, staggered baffles rather than one long one running the full length of the barrel.
It occurs to me that, if someone had one of these on a sloping yard, they might want some brackets on the ends. Slide a 2x4 through the brackets as a "stop", or as a handle to give leverage in turning it. The bracket would also give a gripping point for lifting the bottom to tip the barel to dump the finished compost.
>> a door cut on the side on hinges to remove the compost
>> a copperhead problem
I was going to9 suggest propping the door open when not rolling it, to let air in and CO2 out, but I guess you would want a screen door to keep snakes out.
