This is a bicycle cart that is built from a recycled camping cot, only requires hand tools for construction and is SUPER lightweight. I have not seen anything exactly like it on the web so I thought I would share it here.
I actually built this several years ago so I don’t have any ‘in-process’ photos, but I believe there is enough detail in the ‘as-built’ photos and narrative that you can knock this together quite easily. I had wanted to build something from old lawn furniture for some time, but couldn’t figure a good way to connect the pieces until I found that ¾” copper pipe fit perfectly inside the lightweight one inch tubing used in most aluminum furniture. My Eureka moment, so to speak.

First, the list of materials and tools:

An tubular aluminum camp cot – its important that the legs and bed frame are identical in
width and bend radius. Other aluminum furniture, such as a chaise lounge,
would work also.
Some flat aluminum – 1 1/2 to 4 inches in width – a good hardware store should have this
in their metal rack
Some one inch aluminum flat straps of lightweight thickness (easily bendable)
A length of ¾” copper pipe
10 foot length of aluminum conduit
No. 10 x 1 ½ inch bolts, nuts, washers
1/8 x ¼ inch pop rivets
A threaded rod – for the axle – diameter depends on wheel hub bearing diameter
Nuts, washers and lock washers for axle
Four U-bolts
Wheels – I got mine from Northern Tool (on web)

Pop rivet gun
Tubing cutter
Hack saw
Electric drill and various bits

Step 1: Step 1 Assemble the Top and Bottom Frames

First, of course, you will need to disassemble the cot by drilling or grinding off the rivets. Save everything for later. Next, lay the legs on a flat surface facing each other. (See drawing) Mark and cut the tubing. Offset the cuts as shown to add some strength. Next cut a short length of copper pipe – 8 inches or so – and insert it halfway in one end, drill an 1/8” hole and pop rivet the tube to the pipe. One hint here: Drill and rivet one hole at a time or you will find the holes get out of alignment. Install another piece of pipe in the other end of the same leg and repeat. Now slip the other leg onto the pipe and rivet it and you have the top or bottom done. Make another rectangular frame out of the other two pieces of tubing, being sure that it is identical to the first.

Step 2: Step 2 Attach the Side Supports

This is the only really tricky part of the build because you want the two frames to be square with each other and the sides to be perfectly vertical. So it helps to have an extra pair of hands, some clamps to hold the straps in place while you drill and possibly some scrap sticks to tape to the frames to hold them equidistant from each other. First, drill two holes in each end of the straps roughly ½ to 5/8 inch from the ends. Clamp the strap to the tubing and then drill through the tube and attach with the No. 10 bolts. Its better to put one strap on with one bolt only in each end and then put another on the adjacent side or end. This will make it easier to get everything square. I used two straps per side and the front and one on the back (probably because that’s all I had and didn’t want to buy another four foot piece.) Use whatever size and number of straps you like, but be sure to leave the middle of the front open to attach the tongue.

Step 3: Step 3 Attach the Bottom Slats

The bottom slats are made from the straight sections left from the cot. The slat where the axle is to be attached is fastened with four delta shaped brackets that held the cot’s center support. These were made for tubing ‘tee’ connections and worked perfectly. If your cot or piece of furniture does not have these, you could cut them from a wide piece of aluminum or cut the slat extra long, hammer the end flat and bend it around the lower frame tubing. Anyway, put this one on first. You want the axle slightly rear of center. The other slats are attached using the lightweight strap bent in long ‘U’ shaped pieces. Pop rivet these to the bottom slats and then pop rivet the strap to the frame to keep them from sliding. I was actually short one piece from the cot so I cut one from a lawn chair from a set given to us by my in-laws. However, I want to go on record as advising against this as my food tasted odd for sometime afterward.

Step 4: Step 4 Attach the Axle

The axle is the weak link in my cart and you may want to do this differently. I used ½ inch threaded rod because it didn’t require cutting threads or machining and my wheels had ½ inch bearings. However, it limits the load capacity somewhat because it tends to bend with very heavy loads (30 -50 pounds.) Simply cut the rod and attach it with U-bolts as shown. I glued the inside wheel nut in place and used two nuts with a lock washer between to hold the wheel on.

Step 5: Step 5 Attach the Tongue

Cut a short piece of conduit (12-16 inches) and attach it to the middle of the front. You want to be able to slide the actual tongue into this piece and in order to do so, attach the rear by bolting or using a conduit hanger as I did and then attach the front with a couple of U-bolts and two extra U-bolt straps.
The tongue or tow bar is made from the rest of the ten foot piece of conduit. It is the only part you need any special tools for as it needs to be bent in a lazy ‘Z’ shape. However, if you have an attractive girlfriend or wife, have her take it to a plumber and they will probably put a couple quick bends in for free! Insert a piece of one inch pipe (or whatever fits in your piece of conduit) in each end and pop rivet them in place. Insert the tow bar into the other piece of conduit and drill a hole completely through the conduit and pipe for a pin or bolt. Flatten the other end by hammering the copper pipe flat and drill a hole for attaching to the bike. I just use a carabiner to attach to a rear rack or the seat and if you want something more elegant you can attach to the copper pipe or the conduit itself.

Step 6: Step 6 Add Sides

As you have already seen from the pictures the sides are made from ½ inch netting attached to the top and bottom frames with zip ties. This was probably the most expensive part of the project as I had to purchase enough to make about 50 such carts but I’m sure it will come in handy for something. You could use canvas, also, but it will add to wind resistance.
This turned out to be one of my better projects as we have used this cart for a number of things such as hauling stuff to and from the garden, wet clothes to the clothes line and my son and I even yanked it along on a ‘backpacking’ trip in the mountains. We hauled our food and water in it, making the hiking much easier on our shoulders. On rough stretches of the trail it was easy to unload it and ‘portage’ around obstacles since it is so light.