Mich. Comp. Laws § 445.618: Molder's lien.

Sec. 8.

A molder has a lien, dependent on possession, on any die, mold, or form in the molder's possession belonging to a customer for the amount due the molder from the customer for plastic fabrication work performed with the die, mold, or form. A molder may retain possession of the die, mold, or form until the amount due is paid.