homemade outdoor diffuser

Shower curtains. Even the clear ones offer a little diffusion. Fabric stores have a great selection of sheer material, you can warm it up or cool it down by also choosing off white casts. i'm interested in the other answers that follow too.

I use the shower curtains also. They make a ribbed version in clear plastic. Easy to use in single or double layers and the size is about as big as you can easily handle. Cheap and readily abailable at local-Mart. Washes easily. (yes the wind sometimes wins) Work well indoors too.

I would try painter's masking plastic in 4 mil. thickness. It's very cheap, thin, and not completely clear. It will also make an effective sail, so anchor your frame if wind is a possibility. Good luck.

We use silks in the movie biz that is quite pricey, i's sure fabric stores sell something similar. Other stuff like Opal, Hampshire Frost, and 251 isn't fabric but are made by Lee and Rosco is available in 48" wide rolls. Its about $6/foot but you can get partial rolls for much less at some rental facilities. We use shower curtain stuff quite a bit also. Look at mattews studio equipment's site or modern studio equipment too.

There are many types of nylon or rayon that are quite thin, and mimic the properties of silk.Check out a large fabric store.

Polyester fleece made for horticultural use. It's available at most large horticultural suppliers and is cheap.

plastic, as in shower curtain, while it will work on a strobe (somewhat) it does create too much of a shadow outdoor. Visit a GOOD fabric store. There are many materials, as suggested, that will work great.

forgot: if you are using PVC pipe for the frame make sure it will not fly away when the breeze or wind picks up.