A fearsome skull that holds a puzzling secret. Hidden in the base of this battle-scarred skull is a secret plug that, after solving the cylindrical puzzle within, can be removed to allow coins, gems and other valuables to be hidden within the skull. The puzzle cylinder can be redesigned to allow for more difficult puzzles without having to re-print the entire skull.
The two halves of the skull each have indentations that fit two standard 8x30mm wooden dowels (the kind that you get with most IKEA) furniture. This helps align the two parts properly when assembling. If you don't have any lying around, the design includes a dowel for you to print and use instead. I glued the two parts together using standard contact glue: the kind that has to dry for about half an hour before putting the two pieces together. When the two pieces make contact, they are instantly stuck, so there’s no adjusting later. The dowels help here because it’s impossible to misalign the two parts. Also they provide some extra sturdiness.
I filled the seam with some plaster filler (the kind used to hide seams in drywall) and lightly sanded it down. With some more sanding and painting it should be possible to make the seam near-invisible, but I found it good enough as is.
I used a cream-colored spray paint with a chalky finish as a base coat. I then made a wash of some umber and sienna acrylic paint (extremely watered down) and used it to fill in all the little cracks and ridges and give it more depth. Some detailing was done one the teeth to make them stand out individually a bit more, and some cavities like the nose and eye sockets where colored somewhat darker to give them a bit more depth.
I painted the part of the plug that’s visible from the outside, but declined to paint the maze, figuring the paint would scrape off in operation as well.
A single layer of transparent matte finish protects the paint job.
Altering the original design
I took MakerBot's skull model and used the Sculpt feature in blender to make it a bit more fantasy-like, as if it's an orc skull or just an angry looking, mangled skull. I pushed the 'eyebrows' down to give that angry, sloped forehead look, slightly skewed the nose and cheek bones to make it less symmetrical and made a few dents and gashes in the forehead, to make it look somewhat battlescarred. I also removed some of the teeth and filled in the gaps.
The original model had two rectangular indentations for the lower jaw to fit into: I was not going to use the lower jaw so I filled those in as well. I was planning to put the cylinder puzzle for the secret compartment in the base of the skull, where the spine connects. This required cutting out a circular section and removing the MakerBot logo stamped within (sorry MakerBot). This section was later placed on top of the cylindrical puzzle piece. Two small pegs were placed in the resulting hole, that would fit into the "gutters" of the puzzle and keep the cylinder in place.
I also used two spheres to hollow out a reasonably large space inside the skull, so that it would accomodate the cylinder and whatever objects one would want to hide inside it.