Where can you buy and what type of material have you made a BIAB with? Specifically:
-Name/brand/type of material
-Dimensions of raw material and final bag
This bag holds at least eight pounds of grain. I BIAB as my pilot system, making 1-3 gallon batches on my stove.
A friend of mine thinks any fine nylon mesh will work. You could make one from materials found in an arts & craft store like Michael's or Beverly's Fabrics.
This is what I used:
It is sold as a curtain, it comes with two sheets measuring 94" X 110" and is made of polyester voile, don't know the mesh size. I cut one sheet in half and fold it in half when I use it to line my insulated bottling bucket mash tun. So my "bag" is 55" X 47" folded once. I rinse it off and toss it in the washer with my hop bags after brewing. It cost $5 US, and is 4 times the material I needed.
I have tried two. I've used 100% polyester voile curtain material. You can find that at pretty much any fabric store and buy it by the yard. With that, I never bothered making a bag and things worked out well.
I recently decided to try a sparging bag in my now-insulated 6.5 gallon bottling bucket as an alternative, and I feel like I'm getting more positive results with that method because I can still drain through the grain bed for filtration (and you can lift it by the spigot for faster drainage).
I don't know exactly what brand it is, but it might be Bru-Heat. I purchased it from my LHBS and it is called "Sparging Bag for 6.5 Gallon Bucket." http://www.home-brew.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=EMP3373&Category_Code=BRUH