Making Clip On Gunwhale Clips

This is a bit of an experiment, so we'll see how it goes, but I would really like to make something that can clip on to the gun whales of my boat that would not need anything screwed in. I need this for a tent cover and also to be able to place fenders in different positions, depending on what i'm doing. So I get an idea from another product and then see what I can come up with using my 3D printer!