Bookbinding clamp to use on wetted cardboard or chipboard to make even curves for the spine of a hardcover book. No supports needed to print, does require epoxy/glue to connect the parts, or can plastic weld with a soldering iron.
To use, have your already cut-to-size chipboard in hand, wet under the sink, and place between the two halves of the clamp, applying even pressure on each side with light clamping. You can also use layers of cardboard from soda/cereal boxes with glue spread out between them, then clamp between the two halves.
The author marked this model as their own original creation.