<Snipped quote by Double Capybara>
If @Frettzo or @Scarifar or anyone else is interested in taking the Magic Items portfolio, then they can have it instead. I have plenty of prospective Portfolios to choose from. But while Teknall might be our resident technology god, he is also the god of Crafting, and has an intimate knowledge of all the things the gods (except Vowzra) wrote on the Codex including magic. Making magic items falls within the reach of Crafting and within his capabilities.
Perhaps, as Frettzo said, it would be best to take the stance that something like the 'Magic Items' portfolio falls under both Crafting and Magic. That is not to say that Teknall cannot create magical items anyway with the Universe's intrinsic magic energies, or that Astarte or Niciel (or Belruarc! You forgetters, you!) cannot enhance weapons by imbuing them with the Universe's magic or their own particular brand, but for any of them to assume the 'Magic Items' portfolio they would require both Crafting and Magic domains.
Either way, Magic Items are so generic and universal to gods that it's difficult to see what difference having a portfolio over them would make, other than making it possible for Teknall to craft them and imbue them with magic without spending one Might or a Free Point.
Looking at the others you're considering though, the only ones I can see having potential issues are Electricity and Metal.
Electricity is just energy, difficult to claim it under a Crafting domain - though there is no denying that Teknall could craft things which enable him and others to manipulate Electricity (perhaps an Electricity Manipulation portfolio? I feel there may be a better way of putting it ^^').
As for Metal, it probably falls under more of an Earth domain, though something like Metal Crafting doubtlessly falls under a Crafting domain, just as Wood would (xD) fall under an Earth/Nature domain, but Wood Carving would fall under a Crafting domain, or Stone Carving (!! isn't that very important at the city-building stage of civilisation?)
In any case, Domain (Portfolios) are inherently flexible and there are a lot of grey areas, but what's discussion for, eh?