Prototype 2 of an iris diaphragm style compass. largest diameter 12cm 4.75", smallest diameter 6cm 2.5".

Moves smoothly and holds position fairly well, but is a bit too loose to draw as consistent circles as I would like. Looking for a middle ground between tight tolerances for a sturdy frame and loose tolerances to allow smooth movement. Will also be designing a smaller version to cover circles from 0-6cm 0-2.5".