how to build a stretch cargo/people bike (long bike)

So, you've been on the xtracycle site, and wondered: why are they so expensive? Well, I don't know. But, here is how to make something equivalent cheaply and (relatively) easily. Basic welding is required. Have a fire extinguisher on hand. 

Step 1 Tools and materials

Materials you will need:
- 1 good bike
- 1 donor bike
- some scrap tubing (i had a spare rear rack lying around that i used)

tools required:
- welder
- angle grinder or hacksaw
- bike chain tool
- some form of clamps (i used my brother)
- a jig of some sort. I just used an old gutted microwave to stand the bike on.