The eMac swivel base can be hard to find. It comes in two sections that are loosely bolted together so they swivel like nested bowls. I happen to have two of the LOWER section only which is not much good without the part that attached to the bottom of he emac. Using an actual upper section as a reference, I modeled and printed a new upper section.

Another challenge is the hardware. Apple appears to use custom machined stainless steel parts for the original, but you can assemble this without cheaper, easy-to-find items from a hardware store.

To assemble this you will need:

1. The LOWER section of an eMac swivel base. Until someone wants to model this part, what I have here is just the upper section,
2. Three 16mm M4 screws. This is hold the upper section into the existing mount points on the Apple eMac.
3. ¼ - 20 x 2 inch bolt
4. three 1-inch fender washers
5. one steel sleeve ¼ x 3/8 x 1
6. one nylon washer
7. one ¼ - 20 jam nut
8. one ¼ - 20 self-locking nut.

You do the assembly like this:

From the bottom:

1. 2-inch 1/4 -20 bolt
2.  1-inch fender washer
3. Plastic base (lower section)
4. 1-inch fender washer
5.  Jam nut. Tighten this down.
6. Steel Sleeve 1/4 x 3/8 x 1
7. Plastic base (upper section—3D print)
8. Nylon washer
9. Self-locking nut on top, tighten down against the washers below and steel sleeve.

The jam nut is thinner/flatter than a standard hex nut. This is important because the combined thickness with the washer cannot sit proud of the top side of the lower base section. This is because the mating base part is like a bowl that has to sit down flush over this and clear the nut (though the bolt goes up and through it).

Next, you slip on a “Steel Sleeve” which is 1/4 x 3/8 x 1. It’s one inch high and 3/8 OD which is perfect. At this point you can place the 3D printed base upper section over the post, top with a nylon washer, another 1” washer and self-locking nut. Done.