- In 1960, he founded M&R Marking Systems, Inc., which manufactured and distributed hand-held marking products. The company became the largest manufacturer of marking products in the world.
- In 1978, Len invented and patented the Self- Inking Stamp. The design became the standard by which all other self-inking stamps worldwide were developed.
- Throughout his career Len planned many conventions and meetings.
- In 2000, Len, and partner, Hallie Sculler, established The Great Office Escape (legal title, Coventry Associates, LLC).