Rubik's Rod - no colors

https://www.thingiverse.com/GroznyEntertainment wanted a design that was a little sturdier, so I took on the challenge!
I designed this with a rod down the middle, and then used printed symbols instead of color stickers because I was too impatient to wait for Amazon to deliver. I deliberately chose mostly non-alphabet characters as I think that helps with the magic, but it is configurable. Make sure to not mess up which characters are the same!

I had quite a challenge trying to keep it from sticking.
In the end I think that the variable "gap" is actually twice the eventual gap between some of the parts. (In other words you have to set gap to a larger number than you might think)

How to do the magic trick is something you will have to practice, as it involves a very little bit of slight of hand. The magic sequence is "O :X#+" from either end.

Just added V6, that version includes rounded corners (by request). Note that rounding is done with a minkowski where is very slow to render. If you set the rounding to zero you get the original sharp edges and it is fast to render.