Thanks for sharing this great tutorial.
Real fun.
I prefer to creat the black square like this:
- draw a filled black rectangle with the rectangle tool.
- draw a frame arround it as discribed in the tutorial
Twist and rotate the square like:
- [layers] - [Rotate/Zoom...]
- use the 'wireball' in the upper left corner to twist and rotate the square in the disered postion
(no bothering with figures etc.)
See my first try below.