Get a plastic Skull on Amazon. A smaller skull will work best for this project because it will be glued to a magnetic disk that is about 2 inches in diameter. The skull I am using is roughly 4 inches tall and 4 inches wide (Amazon ASIN B074TR48JR).
You will need a magnetic levitation device, I am using this one. There are plenty of cheaper models available that will work fine for this, but will have shorter levitation distance and less stability (meaning the magnetic disk can be thrown out of balance easier, causing it to wobble or fall). I have done dozens of projects with this model and like it the best (Which is why I sell it!). Side note- it is the exact same hardware that is used in the Lyfe Planter.
Note that this specific device does not come with an enclosure- meaning that all the hardware is exposed and unprotected. I have found that many other levitation devices have LED lights embedded in the base that cannot be removed, which I am not a fan of. If you decide to go with this model, it is important to NOT levitate the magnetic disk before constructing some sort of enclosure for the base. The exposed magnets will be damaged if they slam directly into each other!
For the base, I am using midwest products 6mm craft plywood (Amazon Asin: B002XAWCNS). I came up with a “puzzle joint" design and cut it out on my cnc router using a 1/8” bit. I cut a 3” hole in the bottom to provide ventilation (even though the device runs cool and uses very little power) and glued the pieces together using Gorilla wood glue.
The basic dimensions of the assembled enclosure are: 170X 170X 50 mm with a 12 mm hole for the power cord.
Puzzle Joint box design
Add some cobwebs, spiders, and candles to the scene for maximum spook. Make sure that the base is plugged in and keep metal objects away so as not to interfere with the magnetic field. Hold the magnetic disk about 15cm/ 6 inches above the base. Lower the disk with both hands directly over the center of the base, keeping it level until you feel the upward magnetic force supporting the weight of the disk. Gently let go keeping it centered and level. If it falls, simply lift the disk up and try again. Expect that it will take several attempts and may require some practice to master.