HotSmart® will keep posting all the information required for manufacturing its products on this blog
You can start making your heater prototype immediately; materials are readily available
Iron filings obtained from a brake shop (for free)
For clay I chose red earthenware because it already contains Iron oxide Fe2O3 - which is a polar molecule but actually you can use any clay (The red earthenware is also very common and cheaper) but if you want to start NOW, go ahead; by the way: if you have any questions please let me know
Will you please RT?
(I don't eat on cold, dumb plates anymore - I'm the inventor - but HotSmarts are expensive because they are not mass produced yet)