like v blocks, parallels etc.

Rules

"I saw no other way but to try to create a business for myself by inventing something useful that people would want."

"I had worked at pattern making and used clumsy, fixed-blade try squares. I realized the need of a more handy instrument, gave the subject careful study and drew a design that pleased me, and made patterns of it, sitting at the kitchen table night after night until the small hours."