Caliper pen

The ornamental design for a caliper pen: United States Patent D470780 

Combined pen and caliper:  United States Patent D329252

Plebanek proportional divider: United States Patent D168967

Some thick patents

Measuring thickness: United States Patent 4464840 

 

System of making and recording profile measurements: United States Patent 2703456

Magnetic measuring instrument: United States Patent 2501538