I made this composter out of a couple of old tires and a 55 gallon barrel that the beer store was giving away. I drilled the holes with a 1/2 inch drill bit and cut everything with a reciprocating saw.
Just roll it around every couple of days to stir the compost.

Step 1: Cut a Door

This step is very noisy so wear appropriate protection. Drill 4 holes with a 1/2 inch drill bit. Then cut out 3 sides with a reciprocating saw. attach a piece of steel to hold the flap closed and secure it with a screw. I used rivets to attach the strap but you can use machine screws and nuts. I also drilled some holes in the top and bottom of the barrel to let air in.

Step 2: Cut the Tires

I didn't take pictures of every step because I built this in about an hour. I hope my drawing makes sense. Basically you just lay the tire on the ground, center the barrel on top of the tire and draw around it with a marker. You then take the barrel off. Don't try to cut through the steel belts on the inside of the tire. Drill a couple of holes in the tire instead, then fit a saw through the holes and cut close to the steel belt all the way around until its out. Don't try to cut the circle out that you drew with the marker. Cut close to the steel belt then cut 3 slits from the center of the tire to the line you drew. This will give you a kind of friction bite on the barrel when you insert it into the tire.

Step 3: Put the Barrel Into the Tires

The first tire is easy but the second one can be a hassle. Put the tire on the floor and stab the barrel into it. Then place the other tire on the floor flip the barrel and repeat.
That's it. I hope you enjoy your compost.