This model was made by Gero Gerhardt for the Half Life 2 Mod called "The STARGATE Mod" (www.sgmod.de) it also got edited by Dennis Lehmann who works for the mod as well.
I was working on the project for a few years but eventually retired. They were kind enough to allow me to publish this model for everyone to share on the Creative Commons Attribution NonCommercial License.
I have added a updated version of Part 2 (Middle) and Part 3 (Top). So you can add 5x5x5mm Magnets to make the parts snap together.
http://ebay.eu/29EJiCi 5x5x5 Magnets