Hi, I want to convert a backpack to carry a 4x5 outfit. I have an older model "LowePro Some-Something Trekker" from the 1980s that can hold it all, but I now want to downsize to a generic daypack and use some Photobackpacker boxes I have and maybe some padded dividers too.

I'd like to make a hook and loop board to insert into the back but don't know what to look for at a fabric store or Lowes. What board or stiffener, what fabric, what adhesive, how to fit cut and glue etc . . .

Any one ever done this?