Nice! Now you need to do a textured example ;D

I'm really glad that screw thing exists, I remember doing those by hand a billion years ago before I learned how to rail extrude in Blender (I think it's called something else in Blender but it was rail extrude in Lightwave so that's apparently ingrained in my brain, but it's basically doing a square and then using curves to make paths for the vertices to follow and then extruding your shape along those paths).

There's also a couple of other ways to do similar things with splines, have you played around with them yet? :D