Also, being cast for value (i.e. RR3 to bolt + cast free tinker (without sacing an artifact)
I believe you still have to sac the artifact. Electrodominance still has you cast the spell. The only thing you dont do is pay its mana cost. But I'm pretty sure additional costs have to be paid. This would include sacrificing an artifact to tinker, 3 mana for trinisphere or paying for any other sphere effects.