String-Climbing Monkey Toy

During a recent trip in China, we visited many museums. One work of art in particular stood out to me—a set of 16 silk scroll paintings named "Reunion Of A Hundred Children" by Bingzhen Jiao, from the Qing Dynasty. These scenes vividly depicted children from ancient times playing with a wide variety of toys—kites, yoyos, fireworks. One toy especially caught my eye: a small monkey figure climbing a rope. I had seen something like it before, but never in person, and I had certainly never played with it. I was fascinated—how did people in ancient times create a toy that could climb a rope without modern motors and electricity?

Curious, I researched this unique toy and discovered that its mechanism is surprisingly elegant. It relies on three key points of contact along the rope: one at the top, which uses just enough friction to “grip” the rope while still allowing movement; and two at the bottom, positioned on opposite sides of the rope to allow gripping and releasing. An elastic element pulls the figure upward in repeated cycles, enabling it to “climb.” This reminded me of a simulation study on motion mechanics which ended up finding that a similar model to this one was also very good at walking (Carykh, Evolution Simulator).

I’ve been experimenting with recreating this ancient toy and refining existing designs. The biggest challenge is achieving the right balance: there has to be enough friction at the top to hold, but not so much that it stops movement—along with getting the weight and elasticity just right. The bottom must be able to propel the monkey upwards, but cannot have so much friction that it drags the monkey behind.

We’re using simple household materials, so anyone can try building their own version at home. It's a fun way to explore the ingenuity of ancient engineering and rediscover a piece of history through hands-on learning.

Material

1. Cardboard & paper
2. Toothpicks
3. Rubber bands
4. String

Tools:

1. Scissor
2. Glue
3. Awl (or other tool for poking a hole on cardboard)

Print the template at the correct scale as shown, and cut out each shape from cardboard—two pieces per shape. The exact dimensions aren’t critical, as long as all pieces are scaled consistently. The suggested size is primarily for weight control.

Glue the two body pieces together.

Next, drill holes at the marked points: A and B on the body; A' and C' on the arms; and B', C, D, and E on the legs.

Start by using toothpicks to connect the pair of arms and the pair of legs, as shown. Then, attach the limbs to the body by aligning the following pairs: A with A', and B with B'.

Note: the A–A' joint (shoulder) is not intended to move, while the B–B' joint (hip) should be rotatable. To make the shoulder joint more secure, you can drill an extra hole near A and A' and use an additional toothpick or fastener, rather than relying on glue alone.

Finally, Connect C and C' with rubber bands.

Top:

Cut a small section of a straw (or any small pipe-shaped object). Wrap a rubber band around it to create friction. This is the trickiest part—you need just enough friction for the string to hold the entire figure on the rope, but still allow it to move. The effectiveness depends on the diameter of the straw, the thickness and tension of the rubber band, and the type of string used. It may take a few tries to get the balance right. Once ready, hot glue this piece to the hand.

Bottom:

Thread the string through the leg pieces at points D and E, as shown.

Hold the top of the string with one hand. With your other hand, pull the bottom end down and release it in a smooth, continuous motion. You’ll see your monkey begin to climb! To make the movement more noticeable, we’ve marked sections of the string with different colors.