There 4 different types of leather are used to make these slippers. The top curved piece uses a 3/4 oz veg tan which allows for some rigidity and flexibility. The bottom sole uses a 7/8 oz veg tan to provide stiffness and strength. The upper sole uses a 5/6 oz glazed veg tan with enough flexibility to bend down over the padding. The hidden padding is a 4/5 oz chrome tanned soft leather, and is done in two parts to give extra padding to the heel.
You do not need all of these sizes and could make the entire slipper with any 4-6oz leather.
These stitching holes are punched with 1mm circular irons with 6mm spacing between holes. A wing divider creates the line to follow for punching the stitching holes. A small awl creates the final holes to start and finish the stitching for a neater appearance.