A windmill you light from the inside.

10.8 in tall, and most of that is tower: 8 flat sides, an arched door, 3 windows and a gallery running right round it. Stand it over a tea light and the tower becomes the lantern. The head lifts off, and the wheel on the front — 6.7 in across — turns on a pin 3 mm thick.

The printed windmill on a dark surface: a tapering orange octagonal tower with a railed gallery round it and an arched door at the bottom, a blue conical head on top, and four blue ladder-like sails on the front with a small green pin at their hub. Printed layer lines run round every surface.
Printed in PETG in 4 parts: the tower, the head, the wheel and the pin the wheel turns on.
10.8 in
tall, from the base ring to the finial
8.6 oz
of PETG, in 4 printed parts
6.7 in
across the sails, 7.5 in above the desk
21.5 hours
on the plate for the whole set

It is a building before it is anything else.

8 flat sides, tapering as they rise, a gallery running right round and a shell 2.4 mm thick. Everything that moves hangs off the top of this.

The light gets out the way you would.

One arched door, 1.9 in of it, and 3 windows higher up. There is no floor inside and no lid on the base — it is a shell, 4.8 in across inside, and it stands over the candle rather than holding it.

The head is its own part, and it lifts off.

An octagonal spigot 12 mm deep drops into the neck of the tower on the same 0.2 mm of clearance the wheel gets, so it seats one of 8 ways round and sits square. Everything that turns is carried on the side of it.

One pin, 3 mm thick.

It presses 10.5 mm into a 2.8 mm seat in the head and never moves again. The wheel is bored 3.4 mm and rides on the other end of it: 0.2 mm of air all the way round.

4 sails, 24 openings.

Each sail is a ladder of 6 openings in a bar 4 mm thick, which is how 6.7 in of wheel ends up with so little plastic in it — and why 10 mm of bearing is enough to carry it.

Then you light it.

The candle goes under the tower, not in it, and the door and the 3 windows give the light back. Nothing here runs off the flame: the wheel turns because you turned it.

4 parts, and only one of them moves.

They print separately in three filaments and go together once. The colours here are the filament you get, not a key drawn over the top of it.

The windmill drawn apart: the blue head with its sails floating above the orange tower, the wheel slid outward off its axle, and the tower standing on its own below
Apart, in the order it comes apart: the wheel slides off the pin, the head lifts off the neck, and the tower is a tower.
The orange octagonal tower alone: tapered sides, an arched door at the bottom, a small square window, and the railed gallery round its middle

Tower

6.9 in to the neck and 2.4 mm of shell all the way up. It carries the door, the 3 windows and the gallery, and it is what stands over the candle.

The blue conical head alone, with the short cylindrical bearing boss sticking out of one side of it

Head

Drops onto the neck on a spigot 12 mm deep. The bearing boss that holds the axle is part of the same print, out on the front of it.

The blue sail wheel alone, face on: four ladder-like arms crossing at a round hub with a small bore through the middle

Wheel

4 sails, 6 openings in each, 6.7 in tip to tip and 4 mm thick, on a hub 20 mm across and 10 mm deep.

The green pin alone: a plain shaft with a slightly wider flat head at one end

Pin

23.5 mm long, 3 mm thick, with a head 5 mm across. The only part of this windmill that has to be a fit rather than a shape.

The same pin, doing two opposite jobs.

Tight at one end, loose at the other, and the whole difference between them is 0.6 mm of bore. That is the entire mechanism of this object.

Close on the head: the blue hub of the sail wheel with the green pin head showing at its centre, the blue bearing boss running back to the conical head, and a narrow gap between hub and boss
The green button at the centre of the hub is the head of the pin. The cylinder behind the wheel is the boss it presses into, and the daylight between them is the running gap.
10.5 mm
of the pin goes into the head. The seat is bored 2.8 mm for a 3 mm shaft, so it goes in once and stays there.
0.2 mm
all the way round at the other end. The hub is bored 3.4 mm on the same shaft, so the wheel turns and the pin does not.
10 mm
of bearing length, with 1 mm of daylight behind it so the hub never rubs on the boss.
5 mm
of head on the end, which is the only thing keeping the wheel on the pin.

What the tower is for.

The windmill head on in the dark with a tea light burning inside the doorway: the flame lights the inside of the tower, the two upper windows glow, and the orange print reads as warm terracotta
Lit, from the front. The flame is inside the tower; everything you can see of it has come out through the door.

The base is open and 4.8 in across inside, so the mill goes over the candle instead of holding it. Lift, light the wick, put it back down.

In daylight it is a printed building with a wheel on the front. With the candle under it, the door and the 3 windows do all the work and the tower reads as one lit shape. Neither state needs anything from the other. The wheel turns cold; the tower only ever has to stand there.

The bottom of the tower close up: the arched doorway open to the inside of the shell, the underside of the gallery and its brackets above it, and printed layer lines running round every face
The door, open to the inside of the shell. There is no floor in there — the desk is the floor.

What arrives.

Overall
6.7 × 5.2 × 10.8 in, standing on its own base ring
Tower
8 sided, 6.9 in to the neck, 2.4 mm walls
Sail wheel
6.7 in across, 4 sails, turning 7.5 in above the desk
Weight
8.6 oz of PETG
Printed parts
4 — tower, head, wheel, pin
Print time
21.5 hours for the set
The joint
3 mm shaft, 3.4 mm hub bore, 0.2 mm clearance
Inside the base
4.8 in across, open to the desk, for a standard tea light
Openings
one door, 3 windows, and 24 of them in the sails

4 printed parts and one tea light — and the tea light is the only thing here that did not come off a printer.

The windmill straight on from the front: the sails crossing in front of the blue head, the gallery ring, the arched door, and the octagonal base ring it stands on
Straight on, sails vertical and horizontal. This is the widest it ever is.