Every year my family has a contest to see who can make the best gift wrapping job. My little nephew LOVES trucks and construction equipment. So I figured I would make some trucks drive around on the lid of a box for him. I went through a few ideas and bounced some ideas off of my friend Ben. We came up with the idea of dragging the trucks around with magnets. Now anyone can make stuff go in a circle. I wanted to up the ante a bit and have the trucks drive a serpentine path. I came up with the idea of using scotch tape as a conveyor belt.

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Step 1: Materials

Foam core board- you can buy this from $1.25 to $7.00 per sheet so shop around.
Poster board- wal mart 97 cents per sheet.
foam sheets (for trees and fish) $1 for a bag of assorted colours
exacto knife
scissors
rubber band
3 toy trucks $1
clear tape
patience (not pictured because I used it all up)
some sort of motor / gear / wheel system
battery holder

Step 2: The Road and Grass

I started out by taping some sheets of paper together, laying them over the foam board and tracing out the shape that I wanted the conveyor belt to follow. I cut this out and it became the template for several layers in this build. Using the template I made a road from black poster board. This was glued to green poster board which was glued to foam board. The template was used to cut all this into two pieces, an inside and an outside and the gap between the two was widened to allow the pushers to come up through.

Step 3: The Trees and Lake

Trees are easy, just cut out two similar shapes, make a slot the thickness of the foam in the bottom of one halfway up and the other from the top halfway down. Slip the slots together and you have a tree. I used hot glue to secure them to the ground.

The lake was cut out of the ground, a strip of blue poster board was glued around the perimeter and a blue bottom was taped in place. A sheet of clear plastic wrap taped under the grass gave it a neat surface look and held the foam fish in place.

Step 4: Conveyor System

Using the road template, I created guides on the insides of the curves. I made them from stacked foam board glued together and put a strip of poster board along where the tape would run to provide a smooth surface. Then I glued them onto a piece of foam board. The tape was 3/4 of an inch wide so the guides were just a tiny bit higher than that. I laid out a length of tape sticky side up on a table. I taped down both ends so it was tight and very carefully laid down a second length on top, sticky sides together. The tape is easy to splice with more tape so if it is too short, make more to add. If its too long, cut it shorter and then run it around the track to get the exact size and splice it into a loop. I used some clear plastic from some recycled packaging to create the pushers. these stuck up enough to fit under the bottom of the trucks and catch against the bumpers. Doing this allowed the trucks to be picked up or placed down while the system is running. The plastic is hard to see and quite flexible so no one could hurt themselves on them.

Step 5: The Drive System

By far the most frustrating part of the build. I have an AC geared motor that would have worked perfectly but I did not want to have to plug the present into the wall. Finding a dc motor with a gear system that had enough torque proved to be time consuming and frustrating. I ended up using an old toy my wife had picked up called capsela. I used to play with it as a kid and it seems they just decided a few months ago to stop making it. It came with a motor, battery holder (1 aa was too small), gear system and wheels to drive. It seemed almost perfect. I used a rubber band and some more foam board to build a mount and spring to tension it against the tape. On the other side of the tape was an old wheel from a broken rc car. I ended up using 2 d cells to make it run.

Step 6: Holding It All Together

I made something similar to a mortise and pin woodworking joint. This allowed precise positioning of all the parts. Each one was glued to the bottom of the ground and pinned through the converyor system base. There was a slot for the pin to go through and the pin was a wedge shape to jam everything into place.