Last year, I tried the “gutter hooks” listed on Amazon. Those seem like they'll work until you get up there and see how gutters are actually designed. Gutters don't have a vertical lip as you would imagine. Instead, they're horizontal.
These go on the gutters on my new KB home. You may need to modify them a bit for your specific gutters before you print a ton.
I print them with 100% infill and it takes about 7 minutes per on an Ender 3. I needed about 30 hooks, so it takes about 3.5 hours. No supports or rafts needed.
The author hasn't provided the model origin yet.