Thought I'd share this idea I had for those of you using the Vivitar flashes.
I made a gel holder out of some clear file folders by cutting a 3.25x2" rectangle using the bottom edge. I sealed one edge with a folder label in order to easily insert and remove the holder. You can also stack the gels.
Alternatively you could seal all the edges and write the name of the gel on the side.
There will be some light loss due to the fact the plastic is not totally transparent. I'm sure there are better brands to use, this was what was available at the local Walgreens. You could even use colored file folders for other effects. I've even seen some with designs and sparkles which may add a nice texture,.