I use to have a homemade balance board not to long ago. My beefcake room mate broke the crappy board in half.
Another person suggested a skate deck and a PVC pipe. I have never tried that. My balance board was a skate deck and a big bottle of coke filled with water with duct tape tightly wrapped around it. It worked awesome and was fun. Make sure nothing breakable is around when you use one. Put the bong away.
This fall I have been skate boarding more in preparation for snowboarding. Riding a bicycle is good too. Bicycles are low impact and good for your knees. I am one of those seasoned snowboarders that have good knees, it may be because I ride bicycles a lot. I think skateboarding was very effective. I have been snowboarding and I am not getting sore legs.
IT AINT EAZY BEIN STEEZY