Two gaps, and the rocket lifts out.

A 7.3-inch launch tower in 6 printed pieces. Two cradle arms clasp the body tube below the nose cone, and a fin-skirt collar seats the rocket on the base plate. There is no glue in it and no fastener: every joint in the object is one of two gaps.

Overall
4.9 × 2.7 × 7.3 in
Weight
3.6 oz
Pieces
6
The printed launch tower on a studio sweep: a white two-mast gantry whose cradle arms clasp a black body tube under a red nose cone.

The whole thing is 7.3 inches tall on a plate 4.9 × 2.5 in across, and four pads lift the plate clear of the desk.

The fin skirt drops over the tube and seats on the plate. Its bore is Ø28.3 mm around a Ø28 mm tube.

The body tube: Ø28 mm, 2 mm wall, open at both ends. A post on the base plate stands 8 mm up inside it.

Two arms reach in from the masts and stop 0.15 mm short of the tube, holding it across 12.8 mm of its height.

The nose cone is a Ø23.6 mm spigot in a Ø24 mm bore — 0.2 mm of air all round, and it stays put.

6 pieces, no glue, no fastener. Lift the rocket out of the arms and the tower is still a tower.

Two fits, and nothing else

Wrap-around joints get 0.15 mm. Plug-in joints get 0.2 mm. A cylinder sliding into a bore centres itself on the way down, so it can live with the tighter gap; a flat tenon entering a flat pocket has to meet three faces at once, so it takes the looser one. For scale: the nozzle is 0.4 mm across and the layers go down 0.2 mm deep, so the wider of the two gaps is exactly one layer.

0.15mm

Wrapped round the tube

  • Fin-skirt bore, Ø28.3 mm over the tube
  • Cradle-arm pads, over 12.8 mm of the tube
0.2mm

Plugged into a bore or a pocket

  • Nose-cone spigot, Ø23.6 mm into the tube
  • Base-plate post, 8 mm tall
  • Arm tenons into 4 × 8 × 14 mm mortises
Close view of the two white cradle arms clasping the black body tube just below the red nose cone.
The pads meet the tube head-on rather than wrapping it, so the rocket travels straight up out of the arms and nothing has to flex to release it.

Six pieces

Three of them are the rocket and three are the tower it stands in. The arms seat into mortise pockets in the masts, the cone caps the tube, and the skirt fits round its base — so the rocket is a rocket in your hand, and the tower still stands without it.

Tower
base plate and two masts, 4.9 × 2.5 in
Cradle arm, left
into a 4 × 8 × 14 mm mortise
Cradle arm, right
mirrored
Body tube
Ø28 mm, 2 mm wall
Nose cone
1.9 in
Fin skirt
2.7 in across the fins
The rocket lifted clear of the tower: red nose cone above, black body tube between the masts, white fin skirt below the base plate.
The rocket taken off the tower. The two cradle arms stay where they are, in their mortises.
Front elevation of the printed tower, its two masts standing either side of the rocket on the base plate.
Front elevation, printed in PETG.

What you get

A 3.6 oz object that takes about 9.2 hours on the build plate. Set it down, lift the rocket, put it back — that is the whole of it, and two gaps are what make it possible.

Overall
4.9 × 2.7 × 7.3 in
Weight
3.6 oz
Pieces
6
Material
PETG
Print time
9.2 h
Nozzle
0.4 mm
Layer height
0.2 mm
Walls
2 perimeters
Infill
15%