Udi sent us this how-to for a very high quality photo softbox – looks quite professional and worth the effort -

This is a DIY project I have had in mind for a while now. When I purchased my studio flash heads, they came with a couple of small softboxes. Although I prefer to use translucent umbrellas whenever I can (small, light, easy to transport), there are times when a softbox is a better solution. While I could use the studio head softboxes in some circumstances with my small strobes, there was no way of effectively holding the flash in place without a lot of jerry rigging. To this end, I wanted to design a softbox that would be light, reasonably strong and durable, adaptable (double diffuser, grid attachment, barn doors etc.) at a later date and have a quick and easy way to mount the flash.

Aluminum tape is oh so very handy!- Studio Photography – The Best Softbox Ever