These simple-but-fun string-climbing Makey bots are based on an old folk toy. They climb up strings by using friction and alternating tension/slack. Make two bots and have a race!

1. Cut Out Your Makey Bots

Download and print out the parts, and paste them onto a piece of thin plastic or wood, then cut out the robot racers and the swivel shapes on the solid black line.

2. Drill Holes and Add String

Drill the holes in the swivels. Tie a short loop of string to each of the top center holes. Tie long pieces of string (4 feet or even longer!) to each of the bottom holes.

3. Add Straws and Handles

Cut four 2½” pieces of plastic drinking straw. Use cyanoacrylate (super glue) to attach 2 straws to the back of each racer. Angle them slightly as shown. Thread the long strings though the straws and tie a bead or dowel at the end as a handle stop.

4. On Your Mark, Get Set, Go!

To race, hang the loops up on a wall on 2 side-by-side nails. Hold the strings apart, one in each hand, and while keeping a light tension on both, gently pull on one string, then the other. With alternating left-right-left-right tugs, the racer will slide up the strings in little jumps. Quick, keep going: first one to the top wins! (But don’t tug too fast; the climber will stall!) Release tension and the climber falls back down, ready for another race.

For more fun try these:

» Have a race of multiple “laps”: first to complete 10 up-and-back trips wins!
» Team up with partners: one person tugs one string, their partner tugs the other. It’ll take coordinated teamwork to go fast and win!
» If you have a really high space, like over a stairwell or loft, try stringing up the racers with super l-o-n-g strings!)