This is a cookie cutter shaped like a d20. It uses an integrated spring, so it prints as a single piece without supports.
The included OpenSCAD file will let you make different versions as long as you have a round-ish design; it uses one .svg of the outline and one of the inner shapes.
The spring is based on the Ortho-Planar Spring designed by BYU CMR; I re-implemented a version of their design in CAD, it's very cool.
The one in the photo doesn't have the inset lines on the interior shapes, so it makes a dent (tested on play-dough) but doesn't really imprint the design well.
The author remixed this model.
Uses a variation of the Ortho-Planar spring design as the base of a cookie cutter.