Flipframe Trapeze - String Flip Toy (Astronaut / Robot)

This is a small, mechanical string-driven flip toy inspired by classic desk toys (Tricky Trapeze) and simple kinetic mechanisms.
Pressing the two side buttons twists the string just enough to flip the character cleanly over the top bar.

No springs. No electronics. Just geometry, balance, and a single piece of string.
Designed to be easy to print, simple to assemble, and satisfying to use.

How It Works:
Two upright arms support a balance bar suspended by string.
When both buttons are pressed together, the string twists half a turn, allowing the character to flip over the bar and settle back into position.
Correct string tension and only a half-turn twist are the key to smooth operation.

Assembly Level: Beginner friendly
Please refer to included image files for full assembly instructions and illustrations.

You will need:
Printed parts
A short length of string or twine
Small amount of glue (for character only)
No screws or hardware required.

Important Assembly Notes:
Do not pull the uprights together when fitting the string
The string should not be taut
Leave the string slightly loose and test before trimming
The balance bar must be rotated half a turn only
(more than this will prevent correct flipping)
If the toy springs back without the character fitted, the string is too tight
Once assembled correctly, no further adjustment is needed.

Customisation & Remixes:
Characters are fully interchangeable
Remixes are welcome
Please credit Retro Motion Labs if you remix or share

Included:
Base and mechanism parts
Astronaut character
Robot character
Assembly reference images

Final Notes:
This design was developed through physical testing and iteration.
It’s a simple mechanism, but it rewards careful assembly.

If something doesn’t flip correctly, it’s almost always:
Too much string twist
String too tight
Character too light

Fix those, and it works every time.
Enjoy — and have fun remixing it.

Printing Notes:
General
0.4 mm nozzle
Supports: ON (auto) for all parts
Remove supports carefully, especially around moving areas

Structural Parts
(case, buttons, uprights, balance bars, discs)
Material: PETG strongly recommended

Infill: 100%
Layer height: 0.20 mm

Character Models
Material: PLA (recommended) or PETG

Infill: 100% (weight is required for reliable flipping)
Layer height: 0.12 mm recommended for detail