Michigan Compiled Laws, Chapter 259. Aviation § 259.783

(a) Gross weight, including the model rocket engine, shall not exceed 16 ounces.

(b) No more than 4 ounces of propellant materials shall be contained in a model rocket engine at the moment of launch.

(c) It shall be so constructed as to be capable of repeated flights and shall contain means for retarding descent to the ground so that the structure shall not be substantially damaged and no hazard shall be created to persons and property on the ground.

(d) Construction shall be of wood, plastic, paper, rubber or similar materials and without substantial metal parts.

(e) Design and construction shall include attached surfaces which will provide aerodynamic stabilizing and restoring forces necessary to maintain a substantially true and predictable flight path.

(f) It shall not contain any type of explosive or pyrotechnic warhead.