Parametric spiral generator

thingiverse

OpenScad's rotate_extrude module has some significant limitations, particularly in the version I'm using. Later versions have addressed a major oversight - the lack of an angle parameter, but I still needed something similar to how linear_extrude can do twist and scale, and generate spirals by offsetting the shape during rotation. A comment on a forum somewhere (unfortunately, I've lost track of where) suggested using the hull module to accomplish this, which turned out to be an effective approach. I continued adding features because honestly, I just couldn't resist. To be honest, I'm not entirely sure how Customizer's draw_polygon tool works, it only seems to handle simple shapes quite well. Update (2018-12-15): I added a Möbius strip to the sample shapes and fixed a small math error that was off by 1 degree. Update: As pointed out by AKADAP, the hull module is really effective only with convex shapes. As a workaround, you can now perform difference, intersection, and join operations on the shapes, which will allow you to build up non-convex shapes from convex primitives... His solution is https://www.thingiverse.com/thing:1958354