Whoa… didn’t get that at all.
Yep – that was my takeaway from Step 4 in the Instructable:
Use a pointy (not sharp) tool to gently draw a line around the edge of the leather about an 1/8" from the edge.
… seems like a textbook example of scoring (coming from experience papercutting).
When I work in a new (to me) material, I tend to be very literal and attempt to follow instructions to the letter. Didn’t want to come back and say “well, this didn’t work out at all” and have it turn out it was because I hadn’t included the absolutely critical score line.
As an instructional designer, my pet peeve was end-users that wouldn’t follow procedures, then griped about poor outcomes.