There are many places you can go to for free instructions on how to build a round, wooden hot tub. You don't have to spend money for a fancy book at a bookstore. Instead, go to places such as YouTube or AlmostHeaven.net for step-by-step instructions. You may have to fish around a little as the quality of turorials will range, but you should be able to easily find an online resource guide for how to build your hot tub.