@mur2501 .. wow. I have yet to see a Computer Science student here doing that. We had to study lots of maths and logic, but not drawing, heh.
The roller rulers are intended to be a cheap replacement for a proper architect T-ruler or the wire fixed equivelant. A T-ruler only works on an architects table where a roller ruler you can use on any notebook anywhere.
The idea is that you can move the ruler up and down and the lines will remain parallel and fixed as long as you dont lift it. Then you can pule triangles or protractors on top of it to create various angles.
@freemo
Aaahhh, ok that's nicely explained. Dad and me use the hook-ruler regularly when DIYing up with planks.
I think I'd probably still use normal rulers instead of those rolling things. I fumble way too much.
@mur2501