Thank you. Making your own disks is kind of an interesting idea. I wonder if you could print one out on a 3D printer? I can think of lots of cool custom designs. In general the plastics that are used for the disks are specialized for flexibility and durability though. I'm not sure if a 3D printed one would hold up well but maybe you could coat it with something after you print it out.

Maybe wood might be an option but I'm not a woodworker. Or possibly hammered metal sheeting and thick paper rims? I'm not sure if that would be safe to be throwing around the park though.