Hi Todd, sorry its taken me a while to reply.
The Gate is fairly small for the 20mm miniatures it is designed to go with. I use mine for my 15mm Stargate System Lord army for Alien Squad Leader (ASQL).
----------The Gate with 15mm figures (in the forground).--------------------------------------------With a 20mm Shieldwall Jaffar
It is an elipsoid shape, measuring (externally) 48mm by 42mm. Total height is 52mm
It comes as 2 (almost) identical halves which I found glued together easily with a minimal amount of filling.
The Gate is cast in resin, with the DHD in white metal.
(I presume they dont picture it on their website to avoid any C&D problems)