[ OT ] How would you scientificly explain this ?

What you are describing is a philosopher's stone in the mechanical sense. It is something that can produce anything ( Or in the traditional sense the stone allows one to transmute any given material in any other given material ) 
 
 I would suggest looking into Full Metal Alchemist Brotherhood for inspiration. As that features an equivalent exchange mechanic that despite looking like magic has some consistency and formulaic rules as to how and why it works 
 
 I'd use narrative examples that liken it to alchemy made real. In the real world physics what your describing is just energy. Energy and mass can be set equal. So this is just some pure essence that can be transformed into any form of matter 
 

