You buy a trike, or build a trike frame. There are plans on the internet. After that its all up to you. A bit of Carbon Fiber here, some fiberglass, PVC pipe, a few zip ties, bike parts, car parts. Find a junk pile, and don't be afraid to use it.
   Its surprising what you can make in the middle of the night with a Dremel, when you don't want to sleep, or think about the pain.
   The you're flying down a back road in your lawn chair eating a sandwich, having a cool drink, listening to the birds and enjoying the view. Have to wonder what the peons are doing right about then 

   How does it handle? Like a F-1 race car. How fast can you go? That is one of those  variable questions. On the Black Trike, on flat ground, under my own steam, setup for touring, about 48 mph for a mile, cruise at 20-22 mph. How is it on a steep down hill? More fun than you should be allowed to have. If you want to make some money, take bets from the Bicycle riders that think they are fast to race down. A Recumbent Trike can go faster, corner better and brake better going down hill than any Bike. Its all matter of physics. Smart Bike riders know this is a sucker bet and won't take it. But you get people who think because you have three wheels and are laying down, that you're slow and unstable. Up hill is another matter. I do 6.5 mph up hill all day long. I can't get up on my pedals and get leverage from my body to pedal any faster. When I get to the top I won't be out of breath or anything, and if I want to take a break I can stop anytime and just set a brake and relax. I just have to accept that I'm never going uphill fast. downhill, or on the flats is another story. My Blue trike on the other hand is setup for speed. Its top end is in excess of 60 mph and will go up a hill at about 15 mph. I'm not finished building it yet. I get two hours on the Ford test track this Spring. If neither the Blue Trike nor I break, I have every intention of posting some good numbers.