If you want to print a well-functioning stamp you need two different materials: PLA (or ABS or PETG) for the holder and a more flexible material like TPU for the stamp itself.
Of course you can print the stamp in two parts with different material and glue them together.
In the attached PDF-file I describe how you can do this with a single extruder printer in a single printing process: You change material during printing, and you don’t need any glue.
The author marked this model as their own original creation.