The water holds the cloud up.

Nimbo sits in a hot tub, watering a cloud, and the water runs uphill. Turn the coral key on the front of the tub and the blue jet out of the can pushes the cloud higher. Turn it back and the cloud comes down.

Scroll, and follow the key all the way up to the cloud.

Nimbo, a yellow robot with a navy visor, sitting in a teal tub and tipping a coral watering can; a blue column of water rises from the spout to a white cloud.

It starts at the key.

Everything Nimbo does comes from your hand on the coral key at the front of the tub.

Into the tub.

The key's square shaft runs through the wall and is keyed into a cyan disc, so the disc turns with every turn of the key.

A pin in a slot.

The disc carries a pin 11 mm off its centre. The pin rides in a slot cut across the foot of the water, so as the disc turns it lifts the foot straight up.

The water is solid.

The jet is one printed column. A post inside the tub keeps it upright while it slides up through the bot's watering can and out of the spout.

The cloud rides on top.

The cloud is pegged onto the column. Half a turn of the key lifts it 0.9 in, and the jet out of the spout looks that much longer.

Turn it back to bring it down.

No battery, no spring, no motor. The water is the only thing holding the cloud up.

Half a turn, one straight lift

Engineers call it a Scotch yoke: a pin going round in a circle, caught in a slot that can only go up and down. The slot keeps the up-and-down part of the circle and throws the rest away.

Diagram: the crank disc turns, its pin rides in a horizontal slot at the foot of the water column, and the column and cloud move straight up. cloud travel 0.9 in crank disc on the key's shaft pin, 11 mm off the axis slot in the water's foot
  1. You turn the key.
  2. The cyan disc on its shaft turns with it.
  3. The pin on the disc swings up inside the slot.
  4. The slot lifts the column.
  5. The column lifts the cloud.

Half a turn apart

Nimbo with the cloud lowered: a short blue jet between the spout and the cloud.
Key at rest. The jet shows 0.6 in above the spout.
Nimbo with the cloud raised: a longer blue jet lifts the cloud higher above the can.
Half a turn later. The jet shows 1.5 in, and the cloud has risen with it.
Close-up of the teal tub and the coral wind-up key on its front, with Nimbo's legs and the watering can above.

8 printed parts, and nothing else

No glue and no batteries. Every piece is printed, and each one has a job.

  • Tub holds the bath, the bearing for the key and the post that guides the water.
  • Key with a square shaft that reaches into the tub.
  • Crank disc keyed onto that shaft, carrying the pin.
  • Water column with the slotted foot the pin pushes.
  • Cloud that sits on the top of the column.
  • Nimbo, waving from the bath.
  • Visor that gives Nimbo a face.
  • Watering can, with a hollow spout the water slides through.

Nimbo, in numbers

Size
3.7 × 3.5 × 6.8 in
Weight
2.5 oz
Parts
8 printed
Cloud travel
0.9 in
Print time
7.0 hours
Power
Your hand on the key