Came across this instructable item and it made me think of a book I bought recently.
http://www.instructables.com/id/How_To_Build_Your_Own_Pedicab/
The instructable goes over how to build a frame to tow behind a bicycle, the frame has a bench seat, and you could set up a "pedicab" business that way. The author of the instructable did so himself.
The design is very much like the "grid beam" system that I came across a couple weeks ago. The idea is rather than weld a structure together your first few design iterations are beams that bolt together. The beams preferred in How to Build With Grid Beam are square tubes with holes drilled every couple inches. This is very flexible and lets you quickly tear apart and reassemble a frame design idea until you get it right.
Here's some photos: http://grid-beam.com/photos.htm .. plus the book (linked above) has plenty more examples. A lot of the examples are for furniture etc, but they've built several electric vehicles using the grid beam idea.
Well, this grid stuff looks pretty simple and easy to fix screw-ups. Another book around the shop is How Much Does It Weigh? found at http://www.Robobike.com
I built the Electric Limo in a couple of weeks and my son is working on the battery powered recumbent. Both of these projects use aluminum square tubes, no welding required
Ride safe
Yeah... I've done a small bit using this methodology to mount saddlebags on my electric motorcycle. It's let me redo the mounts several times. If I had welded mounts instead such as welding the mounts to the frame, I would only have been able to do it once and then the been stuck with whatever misdesign I came up the first time around. But being able to unscrew everything and redo it easily has been nice.
The robobike.com site had reminded me of Atomic Zombie .. I've bought a couple of their plans and while those are neat plans, the frames are welded etc.
- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki