It all started with some scrap MDF:
UPDATE: Here is the ebay listing.

I cut the circular base using a router and some scrap wood as a circle cutting jig:

Resulting in a perfect circle:

Using the router, I then cut a rabbet around the edge of the base:

Here is the completed rabbet with the motherboard and fan. This is a mini-ITX motherboard:

Next Steps
Here is a picture of the 12″ diameter steel hemisphere:

And here’s a little jig to route out the fan hole:

I used my drill press to cut the circles, which provide ventilation as well as holes for wires:

Here I’m gluing the four feet on the underside of the base:

Primer and Paint
Painting was very time consuming. Here is some primer on the hemisphere:

And some paint on the base:

Metal Brackets
I used some aluminum stock to fabricate the front panel (power, reset, and LEDs):

And the hard drive brackets:

Here we see the Raptor hard drive and fan mounted to the base:

I used threaded rod, washers, and nuts to suspend the motherboard above the drive:

Nearing completion:

With the painted cover, with holes for eyes and salvaged antenna:

Here is the final product:

All of these pictures are on Picasa Web Albums.
For Sale
Here is the ebay listing.
Now that Android is done, I don’t have much use for it. The specs are as follows:
Keyboard, Mouse, and monitor are NOT included.