Ok, the "Star Gate" doesn't seem possible. I've tried several effects for randomness. Here's what I came up with. I think I'm done and these are the final possibilities. These are all animated gifs so you can see how it truly looks like.
http://istariareference.com/portals.asp
Portal 1 was the original idea.
Portal 2 is the same as Portal 1, except effects are on the outter ring.
Portal 3 is the same effects as 1 and 2, except applied to the trim.
Portal 4-9 are random effects, applied to trim.
I used orange in the all the examples, but different colors will be applied to each of the 5 portals.
It seems I can't redo/edit the poll on this page. Well I can, but it seems it will still remember everyone who voted. Even if I change the poll, those who've voted would not be able to again. I will likely put another poll on a different page for these later on.