Not content with a "crappy plastic Thor's hammer," Caleb from Hackaday made himself a Tesla-coil-equipped Mjolnir with a tiny, 80,000 volt Tesla coil in its head. It shoots lightning! Lots of built photos on the Hackaday site, too.
I had seen some videos of [Staci Elaan] showing off her battery-powered coils and I really liked her results. I figured, with her experience, she could probably do a better job than I could on getting the most bang out of a small package. She was happy to be involved and delivered a small 12v powered coil for me to work with. I should also point out that the coils [Staci] makes are usually donated to educational groups. This woman is awesome.
She had built this big flat head on it, with the initial plan being that it would be the front "face" of the hammer. It didn't really work out that way though. I ended up having to increase the size of the head a bit and change the orientation of the coil. I experimented with different types of foam and you can see in the "making of" video what I finally ended up using. The blue insulation board you see in the pictures melted way too easily.