5 model

Free

Radial Engine, 8 cylinder

Thingiverse

Free

Radial Engine Assembly

Sketchfab

Free

3d Printable Radial Pneumatic Engine

Sketchfab

Free

Openscad, 5 Cylinder Radial Engine.

Thingiverse

Free

3d Printable Air Balloon Engine for LEGO

Sketchfab