Hey David, sorry for my late reply. Chrome tanned is better because it's softer, thinner and easy to fold. I used a 0.8mm leather which is soft and a bit stretchy. I wouldn't use vegetal tanned for this model, it's too hard and too thick. For the triangles in the corner, you need to leave at least 1 cm whatever the size of your pouch (explained at 1min30sec of the video) and make sure you have at least 3mm margin to the stitching line, so that when you turn the pouch inside out it stays flat. I think a smaller version would totally work out well if you are generous with all the stitching margins. Hope it helps ;-)