what is the tier list for ores
The list is not decided fully yet. I have to see what metals/alloys I will support and then work backwards. I think definitely bronze, brass, and steel. This implies copper, tin, zinc, and iron. I think I will simplify steel to be just carbon and iron but I may change my mind if I find another case for aluminum, chromium, etc.. It starts to get unwieldy. It is just as likely that I will leave steel simple and come up with a new magic-sensitive metal/ore that can be mixed in steel or used on its own.
what do you need first to start making magic devices
Basic magic circuit skill and a couple tools and a whole bunch of materials. The basic magic circuit skill will cover etching 2D wafers and embedding the circuits. It does not allow you to reverse engineer other circuits. Different skills and levels will let you lock a circuit such that reverse engineering at too low a level will fail and/or damage the circuit. This may be one of the few cases of skill level escalation in the game because I need a way to lock a wafer at "infinite" level to handle the magic devices that are really code inside the engine and cannot ever be reverse engineered. And it allows for trade secrets and so on.
If you do not know how to mine and cut the gems, etc. then you will end up having to buy a lot of premined and precut materials. And gem mining and cutting is its own complex skill tree.
Magic materials are supposed to be black marble wafers, sand, glass, gems, and crystals. Additional magi-mechanical linkages may be necessary to interface the wafer with whatever it is being installed in... and that may depend on the type of energies being used. For example, electrifying a sword may require copper traces where as transferring some other type of energy may require diamond studs.
There may be additional magic creation skills for specific constructs. Like, recently I was conceiving of a memory cell made of sand and diamond dust. A diamond gem is the universal storage medium and can store all kinds of energy... but it's kind of tricky and expensive just for keeping the values of a magic combination lock. So I got the idea that with the proper skill, a magic device creator could mix and arrange silica+diamond dust in such a way to store a single frequency value. It's also nice because the value is recorded permanently at creation time instead of a regular gem which would store energy on the fly. So you could make a combination lock where even someone reverse engineering it would have trouble figuring out the values easily (without quite a bit of experimenting).
There may be other skills for using specific types of energy and/or gem cuts in a circuit. You might know that a step-cut can be used for combining energies but it would take a skill to know how to properly align a step-cut gem in a circuit. ...and really, this gives me a chance to have easily digestable documentation (in your skill journal) while also making magic creation difficult to master.