Here's a bag I finished up recently. The panels for the flap, front, and back of the bag are made of two separate pieces of leather, joined with a turned welted seam (as are the other seams). I'd used this detail before on a couple bags made for other people, but thought I'd make this one for myself.
The bag is made of 2-3 oz leather, dyed with Fiebing's mahogony dye and polished with cordovan shoe polish followed by black polish. The flap is lined with deerskin and there is a full-width divider to create two separate compartments in the bag. A gusset along the bottom adds a little volume.
Larry Luck