Thanks Paul.
MAKING CIRCLES
I follow detailing the chassis. We need to make the trasnsmision and the engine steering wheel. For this, we normally use a compass, drawings, etc.. but not always we make perfect circles.
Some pieces we can to make with this step.

The material that we need. The most important. A glasses. Drill, caliber, scribers (homemade).

With the scriber, we cut the external circle.

With the caliber, we adjust the external circle using a file or the scriber. We have ready the circle.

If we want to make a hoop, with the scriber, we cut the internal circle. We use again the scriber in order to adjust the internal circle.

We have ready the hoop.

An important considerations in order to avoid the deformation of the plastic .
1.You must remember that you need to be patient and to have some practice. The first time, second....you will say

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2.You must to maintain the scriber sharpened.
3.You must not to press strongly.
4.You must to retire the scriber frequently.
to be continue....