How to make a tandem bicycle from two bikes! no welding, no fancy tools needed other than a power drill.
Step 1: parts
you're going to need:
-crescent/ adjustable wrenches
-two bicycles, nothing fancy (possibly a smaller frame for the stoker if you'd like, and if you're picky and want certain cranks, go with frames with square/ taper BB's)
-crank puller (optional)
-basic bike tools
-probably some other stuff I can't remember right now.