This is a low-cost hitch-mounted carrier for a recumbent bicycle -- for about 1/5 of the cost of the commercial variety.

Ingredients:
One "Excess Cargo Carrier" from Harbor Freight, $40 on sale
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=34313

Hardware: About $25
One 8"x6" pressure-treaded 5/4" deck board
One 3/4"x36" steel pipe
One 1/2"x 12" steel pipe
One 3/4" pipe flange
One 1/2" pipe flange

To attach the pipe flanges to the deck board:
Eight 1/4"x2" hex head bolts
Eight 1/4" stop nuts
Eight 1/4" fender washers

To attach the deck board to the cargo carrier:
Four 1/4"x1.5" bolts
Four 1/4"stop nuts
Four 1/4" washers

Two red bungee cords
One old bike inner tube

Step 1: Cut the Board

Cut a 5/4 deck board to fit the length of the cargo carrier. The deck board provides a stiff, sturdy base to attach the pipe flanges.

Drill two holes at each end of the board, and two in the center of the board. Drill corresponding holes on either end of the cargo carrier, and through the 2" hitch bar.

Step 2: Mark and Drill the Holes for the Pipe Flange.

Mark the position of the first pipe flange, and drill the holes. Note: No dimensions are given, because the position depends on your bike's geometry.

Then, drill holes on the underside of the board so that the fender washers and the stop nuts are recessed. This will allow the board to lie flat on the bed of the cargo carrier. Bolt the flanges to the board using four 1/4" bolts.

Step 3: Install the Vertical Supports

Screw the vertical supports in place.
Mine uses two:

One is a 36" x 3/4" pipe with a right angle fitting on the top. This one holds the handlebars. I happened to have an unused bike carrier from Rhode Gear, so I reused one of the rubber holding straps; you could easily use a bungee cord instead.

The other is a 12"x1/2" pipe, which will hold the back wheel.

To protect the bike from dings and dents, I covered the pipes with rubber cut from an old inner tube. A 1.25" inner tube covers the 1/2" tube nicely; the 3/4" tube didn't fit, so I just wrapped the pipe with the inner tube and secured it with a cable tie.

Step 4: Completed Bike Carrier

The finished project!

Lesson Learned:
I mounted the vertical pipes twice. The first time, with the bike pointing to the left, the drive train (the chain and gears) were on the same side as the pipes, which made them rub together. That seemed like a bad idea. So I moved the flanges so that the tall one was on the right instead of the left. Of course, that would have been easier if both of the pipes were 3/4" pipes.