Here is a quick-but-cool little hack inspired by the
permanent way I altered my Honl grids a little earlier.
Using a piece of elastic and two hooks (tiny bungee cord, hair band and two paper clips, etc.) you can mount any grid to any smaller sized flash. I use them to mount my old
Paul Buff grids to speedlights.
Why? Because if you are mixing speedlights and big lights, your gridded accents can usually be handled with low-power flashes. And many people have full sets of grids in varying beams for their big lights but not their speedlights.
Works on big modifiers, too. Using two larger straps in "X" formation allows me to mount the relatively inexpensive grid from my AlienBees dish onto my slightly smaller Profoto dish -- thus deferring the need to purchase the brand-specific beauty grid.
In short, as long as the grid is bigger than the target light/reflector, you can mount any grid to any light. Use two straps for more control and/or tension as needed, and you're good to go.
They take up almost no space -- just keep a few of the elastic hook sets (at your needed lengths) tucked away in your light bag. Like me, you're probably gonna find more uses for them on location, too.
-30-
Remember those nickel-zinc batteries-on-steroids that came out a few months ago? Long-term usage reports are starting to come in. 
