Hand-Sized Magnetic Piston Prototype

I am Rhys and I need a compact, hand-held magnetic piston engine built mainly for prototype testing. The focus is on a basic structure that proves the concept is viable rather than on immaculate cosmetic detailing... (Budget: £20 - £250 GBP, Jobs: 3D Modelling, 3D Printing, CAD / SolidWorks, CAD/CAM, Mechanical Engineering, Product Design, Prototyping, Solidworks)