I've created this thing because I couldn't find a tamper that would fit my moka pot filter (which is only 42mm in diameter). The measuring spoon was designed to match the filter volume.
You can scale the STL object to match your filter diameter. You might also manipulate the height (Z-axis) to achieve interesting effects.
Some brim might be required.
The item is coated with two layers of polyurethane varnish.