A very simple 4 legged GoPro camera base mount with suction cups.
Use:

• 20mm suction cups (amazon link - https://www.amazon.com/Hyamass-Plastic-Suction-without-Diameter/dp/B0749Q8Z5Q/ref=as_li_ss_tl?ie=UTF8&qid=1546725579&sr=8-3&keywords=20mm+suction+cups&linkCode=sl1&tag=zroiy-20&linkId=6eaee4710b3f1f09f5d299962a97ca9a&language=en_US)
• A regular go pro screw and nut (amazon link - https://www.amazon.com/Hyamass-Plastic-Suction-without-Diameter/dp/B0749Q8Z5Q/ref=as_li_ss_tl?ie=UTF8&qid=1546725579&sr=8-3&keywords=20mm+suction+cups&linkCode=sl1&tag=zroiy-20&linkId=6eaee4710b3f1f09f5d299962a97ca9a&language=en_US)

Can be printed without support. Any infill between 20-40 should be durable and strong enough to hold a GoPro camera.