I've made a simple version out of air harden steel. It was too soft and or too rough. It began to transfer metal to its counterpart. A lever, about 10" long, rotates at one end, about the axis (bolt for now) are three dimples about .315" diameter by .08 high. There is a counterpart with identical dimples and axis. The radius of the dimples is about 1/2". It can be up to 1". I'm going to try attaching a photo.