These are simple espresso tampers for 52mm portafilters (e.g. Picopresso).
I experimented with concentric grooves, so I included 2 designs with coarse and fine ones.

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Modified Alfawise U20

No

No

0.2 mm

18%

The grooved tampers need good layer adhesion and slow speed for the first few layers.
I had success without support material even for the coarse grooves.

You might need to sand the perimeter of the tampers to achieve a tight fit.