DIY Photography with Larry Becker: Gels
Option Two: Plastic Frame
This method is based on a tutorial I saw on www.diyphotography.net, where they used a clear, Plexiglass, desktop photo-holder stand, warmed it along a line using a lighter (or torch), and then bent it to just the right size and shape to act as a gel holder. With this option, you can stack your gels in the holder without putting Velcro on each piece of gel.
So, that’s how to add gels to your flash, and it doesn’t have to be expensive. All you have to do now is experiment to see how your flashes blend with ambient lights, or use them for special effects. It will add a whole new dimension to your flash photography.