Sangheili Arum Puzzle (Toy from the Halo Series)

Note: This is still a work in progress, I have since printed three layers and feel confident in the thickness and tolerance to post all the files. Let me know if you have any problems.

Introducing my version of the Arum from the Halo books: "Glasslands", "The Thursday War" and "Mortal Dictata" all by Karen Traviss. This is not an official interpretation, but what I imagine when I picture an Arum based on the book's description and the Halo Wikipedia entry.

So what is an Arum? An Arum is basically a Sangheili (Elite) version of a Rubik's cube, a puzzle with a lot of complexity yet at the same time, very simple. An Arum is a series of concentric spheres with a jem or stone at the center. The way you solve this puzzle, is by aligning a hole that is in each spherical layer until you get to the center and pop the stone or jem out. The idea is to teach discipline and patience to young Sangheili warriors.

An Arum actually shares a lot features with a real world item called a "Chinese Sphere Puzzle" which is a series of concentric spheres carved out of a single piece of Ivory or Jade. But the intent of the real world equvilent is to be ornate and is very fragile.

My take on the Arum has a single hole per layer, other versions as well as the Chinese puzzle has multiple holes. It is also about the size of soccer ball, has layers 1.5mm thick, a tolerance of 1mm and hole diameter of 75mm. I also currently have 20 layers of spheres on file, so print as few or as many as you like.

How this works:
There is a file for half a sphere with a 75mm hole in the center, and a second half of a sphere with no hole. This is such that there should be no need for support if you can print above a 70 degree angle for on that half. Each of the two halves will share the same Layer number. You print one with a hole, one without. Glue the two together and move to the next larger layer. You can also print two halves without holes are drill your own hole if you would like a different size.
I alternatively made spheres with two holes (printing the file with the hole twice) because I was having problems with support remnants interfering with the next layer.
Also don't be afraid to just print the no hole models and just drill holes to the size that you want. With good layer adhesion, drilling is absolutely possible, just take it slow.