It took me home a few flat rings of cardboard. Cut with scissors for a long time. I have set a goal to make the device comfortable to simple.
In industry, these rings are made die-cut stamps. To make such a stamp at home difficult. I took a knife (folding, pocket, price of 22 kopecks), drilled in its hilt two holes of Ø 3 mm and attached circular foot as follows (the circular leg of the enterprise LSSM, price 42 kopecks). Circular leg pencil has a mount, whose top and bottom three petals. Central petals I bent back outwards by 90°, inserted them into the drilled holes of the handle of the knife and bent towards each other.
1 — screw legs, 2 — in circular foot, 3 — knife handle, 4 — petals feet, 5 — blade.
Using my devices, you can cut circles with diameters from 20 to 200 mm.