This thing adapts a mini sized Estes Model Rocket Engine (i.e. size "A") to a standard size (e.g., size "C"). Printed on Makerbot 2 with "medium" settings 10% infill 2 shells 0.27 layer 50mm/s speed while extruding. Print time = 27min. Weight (without engine) = 6g This mount allows the use of the smaller "mini" engines in rockets such as thing:87495 which are sized for the larger "standard" engines.