The inspiration for this build comes from "Sufficiently Advanced" who did a YouTube video showing his build for Thor's Hammer:However, I'd like to change it up a bit. For one thing, it's a bit too heavy. You can see how he tries to handle it and has trouble holding it upright. If Thor is going to carry this thing around for hours at a time during an appearance, it can't be that heavy.
Second, the release is too slow and too obvious. There's a big square window in the side of the handle. He has to put his finger on it in a very specific place, then wait for it to recognize his fingerprint before it finally releases. I've got experience using those readers and I can also add that it will often not recognize the fingerprint. Both things ruin the illusion.
I propose using a pair of security door magnets for the build, each rated in excess of 600 pounds holding force. They weigh less than 2 pounds each, and are already intended to be mounted to something (typically a door frame). They also run on 12v and fairly low current draw (~400mA) Also, rather than 4 sealed lead-acid batteries, I'd like to use Lithium-Ion batteries. They're more expensive, but they're much lighter for the same mAh rating. I'll also use an aluminum frame to hold it all together.
Lastly, my plan for the release system is to use a small arduino microcontroller such as an arduino pro micro which is reading from a compact RFID reader such as the ID20LA. This way, rather than it being tied to a specific fingerprint, it's tied to an RFID tag. The RFID tag can be in Thor's boots such that when he steps up to pick up the hammer, his foot is naturally right next to the side of the hammer where the reader is. In my experience, this is much faster and more reliable than fingerprint readers are. My only concern is about the interference from the magnetic coils. But we'll see if that poses an issue or not.
So that's the plan! Now, to carry it out...