I made my compost bin from salvaged wood from a nearby factory. They gave me the wood for free. All I needed was a portable circular saw and an electric screwdriver. It would be a great learning experience to make your own, possibly not just for the kids
. There's measuring math, constructing 3-D shapes, you can draw a plan and then you've got blueprint drawing, construction safety, friction, velocity, and gravity are all tied into power tools, and probably a million more things I can't think of. The there's the actual composting which is a wonderful lesson on soil composition, Ph levels, etc., recycling, plus a nice little moral lesson on how from death comes life, and compost helps you have a wonderful gardening. And gardening has it's own plethora of learning activities. Sorry, I really love finding academia in seemingly everyday things
. I'm sure you could find directions on the internet if you do decide to build your own. Also it is very empowering as a woman to accomplish something that would traditionally be a "man thing" like construction.
Have fun composting! Jess