Here is what you need to make a simple beauty dish; white plastic bowl, foam board, zip-ties (zap straps), aluminum tape
Trace around the front of your flash. Make sure it is centered on the bottom of the bowl.
Make 2 diagonal cuts to make the flaps
Fold the flaps back 90º.
(Trick - once the flaps are cut, fill your sink with hot water from the tap, let the bottom of the bowl sit in the hot water for about 5 min. to heat up the plastic making it easier to fold back)
Check to see how your flash fits.
Front view of fit.
Draw circle on foam board, about 1/2 the diameter of the bowl.
Apply aluminum tape on other side of foam board, making sure the aluminum tape covers a larger area than the circle on the other side.
Cut out circle with sharp box cutter knife.
Cut slits just big enough for the zip-ties to fit through every 90º.
Bend the zip-ties (you'll see why)
Insert zip-ties through the holes you cut into the circle so the bends in the zip-ties face outward (radiating from the circle)
Cut slits into the plastic bowl just big enough for the zip ties to fit through every 90º
(Trick - you might have to insert a small flathead screwdriver into the slits to stretch them just enough to get the zip-ties through, the zip-ties should be held in place by the friction from the slits)
DO NOT MAKE THE SLITS TOO BIG SO THE ZIP-TIES MOVE FREELY!
This is how it looks finished.
With an omni-bounce on the flash.
Illuminated (with omni-bounce on flash).
I might not be beautiful, but the light from the beauty dish looks good!
Any questions or comments please post them in the comments.