the original one (photo) i made was a bit hefty, it pushed up the shingles, so i thinned it out to allow a fir if flex to keep from pushing the shingles up. this is my first time designing a n interlock idea. so feel free to tweak it. the arrow part fits nicely. print in petg to make it last. and possibly coat with a uv blocker after printing to really make it last. good luck, happy printing.