We've mentioned how to turn an old bike into a cargo bike, but if you're more concerned about transporting yourself, you can easily make your own recumbent trike out of old bike parts, even with no welding or bike maintenance experience.
Oddly enough, the only skills you do need for this project are those involving heavy duty tools: a hacksaw, electric drill, rotary tool, and a few bicycle tools. If you have an angle grinder or drill press, you'll be even better off (though they aren't necessary). You'll also need parts from three old bicycles, which shouldn't be hard to find. All in all, it cost the original builder less than $US250 Canadian and only took a month to build, with no previous bike maintenance experience whatsoever. Hit the link for detailed instructions.