Something not working, or have a request? Open a GitHub issue — we read every report and PhiStruct is actively maintained.
Tap the white ball to see every direction a strut can go from it. Tap one of the glowing holes to place a strut of the currently selected color and length. Keep going from any ball in your build.
Tap the color and length controls in the toolbar to set what the next strut you place will look like — blue / red / yellow / green, lengths 1 / 2 / 3 — just like a real strut kit.
Open ⋯ (File) → Library to browse built-in models, grouped by shape family and difficulty. Open one for a step-by-step guided build (use ‹ › to step, or More → Complete), or toggle a translucent reference ghost and build freely alongside it.
From ⋯ (File): Save / Open keep an exact
.json project file you can reopen later. Export gives you
a high-resolution PNG, a full-color GLB (for Blender/AR/web viewers),
or a centered STL for 3D printing — plus a parts list (color ×
length × count) you can copy to buy or sort real struts. On
iPhone, Save and Export use the system share sheet.
PhiStruct only lets you place struts that would be physically buildable — a strut is never allowed to pass through another strut. If a direction isn't glowing, that placement would cause a collision.
Open a new GitHub issue with your device model and iOS version, and what you were doing when it happened. Screenshots or screen recordings help a lot. You can also browse existing issues.