Hi.
Is there any software that produces on a computer screen, drawings like this old toy did ?

----> http://www.ebay.co.uk/itm/VINTAGE-7...AGIC-RAINBOW-WEST-GERMANY-WORKS-/281136970291

If picky, with controls for colors, angles, amplitude, speed, adding modulation...

 

http://www.instructables.com/id/Pendulum-Art-on-a-Spread-sheet/

According to the comments on the same page, it can also be done with Scilab: http://www.scilab.org/ (think free Matlab)

 

Excellent !
It works with Linux/OpenOffice, just tried. Exactly what I was after.
Thanks !!!