Spindle is a 2.5D geometric art application for iOS, built with SwiftUI and Metal-backed rendering. It lets you design mathematical art through procedural generation: choose epitrochoid or hypotrochoid curve modes, tune fixed and rolling radii and pen distance, then watch the path resolve in real time. You can animate drawing speed, scrub along the path in manual draw mode, frame the scene with a dynamic camera, and keep radial construction guides visible while you iterate.
Spindle is a design tool for explorers of structured symmetry, spirograph-like forms, and expressive line art; join the open beta to try it on iPhone and iPad.