Print the stamps in flexible material, as the design will likely not work if the stamps are printed in hard plastic. The stamps are a taper fit into the handle.
The base has a chamber to fill with plaster or concrete (etc) to add weight to the base.
The stamp ejector pin is retained with a bit of folded (rigid) 1.75mm filament. The filament goes in LAST during assembly.
There is an included DWG file of the stamp patterns, as applied. All shapes other than lips should nest within each other's stamped pattern. This means the circles should fit inside each other, the 5 diamonds should fit in the star, etc.