Simple beam compass

[Christophe Mineau]

HI,
Here is my super simple beam compass, allows to draw large circles, with a centimeter basis radius.
Basically, you need one hole every 5 or 10 cm, plus, between hole 0 and 5 or 10, one hole every cm.
Putting your pencil on one hole, and a pin at the other end, you can draw any circle with radius stepping from cm to cm.

Here below, a circle with radius = 20 - 3 = 17 cm