One of our members picked up some used tires that were on their way to the junk yard. One of the larger ones now lives by the makiwara in my back yard. When I need a break from pounding the makiwara I get out a sledgehammer and pound on the tire. It is a great power workout for shoulders, lats, abs, and even gets the legs moving.
I can spend way too much time doing circuits on the makiwara, the heavy bag, the double ended bag, the chishi, and swinging away with the sledge hammer. Cheap entertainment and a workout at the same time. It sure beats standing on a tread mill at the gym watching Oprah.
Here are a couple of pics: