What I think is neat, is that while it might unbalance the game for a short period of time, they have a kind of built in self limiter, and no one in D&D will really have the skills needed to "salvage" them... They'd function kind of like mini artifacts.
The DM I guess could play around with the idea of letting the D&D characters do something that works like salvaging- like maybe arcana, or thievery, but the DM would be in full control there.
"Well, you pump a lot of magical energy into the thing, and you THINK it's mostly stabilized... but you're really not sure... It's not like anything you've ever encountered before- so it might stop working at a moment's notice..."