I designed of these clips to hold fabric over our raised garden bed to help protect from frost. Our particular raised beds are made out of 2x6 lumber, so the modern 2 in lumber tends to be a 1.5 inches, which comes out to just about 39 mm. So this clip will work on anything in that range. I added some pinchy spots to make unhooking easier. Designed in Fusion 360, printed in PETG with 15% in-fill.
The author hasn't provided the model origin yet.