I just finished three improvements to my Spirit Skull. The jaw is now normally closed and opens on command. the head is magnetically mounted to a 3d printed cervical spine, and everything is mounted in a glass dome. It can be viewed on my YouTube channel: Bill's Magic and Halloween Props. https://www.youtube.com/channel/UCgHMiku6ODYy6xMz2Wmu47w

Very cool. Is there a reason (perhaps weight) that you chose to do a smaller skull size?
Still awesome and you have a new subscriber!

Yes,
1. Many magicians want to keep their packing weight and size to a minimum.
2. Keeps shipping and material cost down (a full-sized 3d printed spine takes a LOT of plastic).
3. The perception that the mechanism and electronics are too big to fit into the skull (it IS packed!), and MUST be in the base....

Due to demand, I am working on a full-sized skull now.