This is the finished bag from the bottom view.
My original plan.
After ironing the interfacing onto the outer bag fabric, I used HeatnBond. I chose the wrong one and couldn't sew through it. I was planning on stitching around at this point with a satin stitch, but I'll likely cover the edges with paint later instead.
I did make my straps differently in that I simply folded it in half and then folded the insides in.
The finished bag with a skilled and large tupperwear inside to show the depth.
The other side.