Indo boards are probably the most popular retail balance trainers aimed at surfers. They're pretty basic in construction, and K Mac at the forum has kindly put together a how-to guide to make your own balance aid. And here's how, based on a 39" x 12" x 3/4" board.
Here are the ingredients
Go shopping at your hardware store to get the bits you need. K Mac suggested that most building sites have these readily available at a "cheap" price, but we're not sure we would endorse this approach.
The first step is to cut down the piece of plywood to your chosen size. In this example it's 39" in length. The off cuts are used later for the "stoppers".
Sand down the four corners to make nice rounded edges. You can also round the edges of all the rails. Make sure you sand them so they are very smooth.
Once you have nice rounded edges, you can use them as a template to make the blocks/stoppers.
Use the counter-sink drill head to make your holes to screw the tail blocks to the main board.
Rounded corners with stoppers attached
Sand down all the edges and stick or spray your own design on it. A bit of customisation goes a long way. If you are painting the board, make sure that you let the paint dry before the next step.
Customise Your Design
Using exterior clear varnish, mix the first coat 80/20 with some white spirits and then leave it for 24 hours to dry. Repeat the varnishing to add another coat.
That's it! You're done. The pipe sits under the board. Balance away!
The finished design