Only 2cm (0.79 inch) in Ø.
Print one piece and see if it fits your application.
I would recommend scaling it up 2x or 3x depending on your need.
Use a double adhesive tape to mount these to the ceiling.

Multi-purpose Ceiling Hook - Versatile and waterproof, making it perfect for hanging a variety of decorations such as string lights, wind chimes, wind spinners, cat window perches, lightweight plants, fake flowers, picture frames, mosquito nets, banners, LED strips, balloons, Christmas decorations, birthday party decors, and more. They can be used on walls or ceilings in the living room, bathroom, kitchen, porch, patio, outdoors, RV, offices, and more.

Originally created to hang some of my Christmas Baubles