Commercial flash diffusers and bounce cards are pricey for what they are - thin sheets of foam and plastic. This DIY version uses a sheet of craft foam and a band of elastic for nearly-free flash diffusion.
Photography site DSLRBlog shares a simple tutorial for turning a sheet of crafting foam (available for about a few bucks at any craft or hobby store) into a DIY flash diffuser. You'll need a sheet of craft foam, scissors and an elastic strap or rubber band. You can download their template or create your own based on the shape of the commercial flash diffuser you're imitating.
Check out the full article at the link below for more details, or check out some of the other clever flash diffusers we've shared with you like this one made from a clear drawer liner or this pop-up flash diffuser made from an old film canister.