Riyeko/Azalea.
I would suggest going for smaller material and a rough frame for your prototype; the two should balance out for a cost-effective approach. As for vanish and silencing—depending on how you set up the magicite circuitry, you can kill two birds with one stone, but I'll leave that to your discretion. For self-destruct—maybe compromise with blowing the circuitry instead of the entire device? As long as we procure metal off-ledger, there shouldn't be a paper trail leading back to us.
At any rate, just take these things into consideration & do what you think is best. Guild can cover the expenses of the prototype. We can review what should be added/amended once we've got a working example. The issues of maintenance & upkeep can be tackled further then, as well.