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. Metal is the preferred material for all key components so the unit can handle repeated cycles and provide realistic performance data. Here is what I expect: – A fully assembled, self-contained model small enough to sit comfortably in one hand. – Reliable reciprocating motion driven purely by magnetic interaction (no combustion or external power once started). – Simple switching or timing mechanism that keeps the piston cycling so I can observe efficiency and forces at play. – Any quick sketches, CAD files or wiring diagrams you create while developing it so I can iterate later. – Short video or live call demonstration that shows the engine starting, running and stopping. If you have an engineering background and access to basic machining or additive manufacturing for metal parts, this should be straightforward. I am open to suggestions on magnet grades, bearing types, or alternative layouts as long as the final unit meets the size and functionality goals above. Looking forward to seeing how you would bring this miniature magnetic engine to life.