#DIY This is part 1 of the math tools that I designed. In this project, my ultimate goal was to design something that costs cheaper than to buy it. As a plus, you don't have to go far to make it. This part is a flat compass. That's right! You don't need a compass. The way this works is that you need to pencils. One pencil starts at the center, and the other at wherever you want to specify your radius. To actually specify your radius, there is an inch wide and a centimeter side. To me, this tool will be even less frustrating than a compass since you don't have to constantly worry about your compass moving and therefore you messed up your circle. I printed this one with .2 mm which worked perfectly, however, I don't know whether other printers will print it the same way as mine did at .2 mm. Therefore, I think it would be best for others to print it at .15 mm, just to be on the safe side :)
Also - I added images of it so you could see how it works!