Unfortunately, I did not take photos as I went through the build. I will do my best to explain the steps I followed.
I wanted this trike to be made completely out of junk, and I mostly got my wish.
Step 1: Front Chassis
The kick scooters had nylon foot plates. These were removed and the frame, which was steel square tubing was cut separating fronts of scooters from rears. The fronts were then placed facing away from each other and welded together.
The front chassis is held to the rest of the frame with bolts so it can be dismantled for easy storage.
Step 2: Rear Frame and Boom
The complete boom (front & center) is from bed frame angle iron.
Cut 2 pieces of angle iron and weld them in the shape of a C channel leaving a gap as a slot to hold bolts. This allows the seat to be adjustable by sliding it along the center boom. The front boom is another 2 sections of angle iron welded together, again like a C channel but this time with the open side facing down and no gap. The bottom bracket /crank unit adjusts by sliding along this and locks in place using a clamp fashioned in the way shown by atomic zombie's plans.
Step 3: Front Wheels
Step 4: Seat
Step 5: Handles and Steering
Steering geometry was set according to information gleaned on the net and from atomic zombie. Look for info on center point steering and Ackerman steering.
The King pin inclination was left at what the kick scooters provided in fully unfolded position. Caster was set using a protractor and then welding the frame in this position.
Step 6: Drive Train
The chain is made from 3 lengths of chains taken from old bikes. The idler pulley was thrown out of a workshop as the bearings were badly worn. I filled it with grease and used as is. It sometimes makes some noise, but for the most part works fine. I've used old garden hose to cover most of the chain that might dirty my pants. Most plans call for routing chain through hose only on the slack side, but I decided to use it on the tensioned side of the chain as well. So far so good.
Step 7: Rear Carrier
Step 8: Conclusion
That in itself eliminates the need for more gears. However, the actual reason I don't have the front derailleur is because I had already cut off the down tube from this bottom bracket earlier, when I had used it in another project.
I could have done a better job, but was short on time, as the summers here are gone in the blink of an eye, which is also why I didn't have the chance to document this step by step.
Atomic zombie has some very nice, detailed plans for anybody so inclined. Please note, I am in no way affiliated with the guy. Just looking at my work will show you I am not fit to linger in his circle.
However, I am pleased with this trike and especially proud to have used mostly junk, which would otherwise have taken up space in a landfill.
I hope this information will help someone else to achieve their own recycling goal.