I had to use two different pieces, as I am trying to use up the odds and ends of my stash:
Wobblerat, that was what I was thinking. It seems like these could be made with separate pieces all around to use up smaller bits. Instead of putting the pattern on the fold, cut extra pieces (four for the outside and four for the inside). A little extra sewing, but a good way to use up smallish pieces. Was there anything different about the construction using the pieced bits?
I still put the pattern on the fold, and cut two of the outside, and one each of the lining for 4 pieces total. If I understand correctly, if you didn't lay it on the fold you would have 4 pieces for the outside and 4 for the lining. With that layout you would have a seam down the front and back of your bag with a different color on either side. You would also have two different pieces for each gusset.
If I were to make a bag with 4 different fabrics for the outside and 4 for the inside, I would manipulate the pattern so the front and the back of the bag were one solid piece, and each gusset were one solid piece. Don't forget seam allowances (I always do!)
From there the construction of the bag would be similar, but not quite the same since the original pattern calls for the gussets to be half pieces instead of whole. I'm sure it could be done, but would take some finessing. I would have to make one to tell you exactly how to do it.
It's a great idea, and I have lots of scraps that would work. When I get a chance I think I'll make one. Thanks for the idea!