This work introduces a modular experimental micro turboexpander system designed to perform air turbine tests of a radial impulse cantilever turbine. The system has high modularity and is intended primarily to test flow-path components which are manufactured by 3D printing and rapid prototyping. System design from the fluid dynamic viewpoint is based on a previously described tool proven and validated during the design of micro turboexpanders in range of mainly dozens of kW. In order to achieve maximal simplicity, the system uses a converted aeromodelling motor as a permanent magnet generator and housing for bearings. Overall parameters are obtained from electrical performance and known generator’s characteristics. The mechanical design then takes into account request of simplicity, modularity and properties of materials in additive manufacturing, especially plastics. First experimental tests show a comparison between different manufacturing technologies and resulting flow components surface roughness and the impact of pressure ratio on the isentropic efficiency.

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