If you're the type who loves the challenge of building your own stuff, building a hot tub from plans might be right up your alley. Hot tubs can be pretty simple or very elaborate, and your level of expertise as a builder should be the determining factor upon which you base your decision to go with a simple or a complex spa.
Once you've decided to build a hot tub, you'll want a good set of plans drawn specifically for the type of spa you plan to build. If you have a local pool & spa store, that's a logical place to look. Ask the employees and really pick their brains. Most of those stores have at least one truly handy person who can be a wealth of information on such projects. Your other in-person option is to go to a local Lowe's or Home Depot and find someone who can help you locate some plans.
If you're not lucky enough to live near these types of stores, the Internet is a great alternative. In fact, even if you do live near an outlet, don't overlook the vast research capabilities at your fingertips. It's as simple as going to Google or Yahoo and typing in "hot tub plans" or something similar. A recent check at Google for that very phrase produced over 800,000 web pages!
Once you've secured a useful set of plans, study them closely. A successful project like building a hot tub is often won or lost in the planning stages. Before you even purchase the necessary supplies, chart out the steps in your own words and enlist the help of friends or family members for the parts you cannot do alone. The more you plan ahead for such things, the smoother and faster your project will proceed.
There is one note of caution when building your own hot tub from a set of plans. Very often, the plans will not include electrical issues. This is, as you know, extremely important, from both an operational and safety standpoint. If you're not an electrician or at least very experienced with these things, get some professional help. It's not worth the risk to guess or rig something that isn't by the book.