So, Opus56 posted a messenger bag that has appropriately wowed everyone in the showoff forum and has graciously consented to let me draw up a pattern for all here. I drew up the hard stuff...all that's left is a (2) 2" straps (1) 28" long for the buckle end and (1) 52" long for the other end.
As to how it all goes together, go over to his thread on the showoff forum. It's all pretty self-explanatory
slotted messenger bag.pdf