I decided to create my own version of a coffee filter holder.  This was designed for #4 sized filters and you will need to mount it with double-sided tape.  You could add holes for mounting with screws if desired.  Wall thickness is 0.1" which makes it a bit on the flexible side but it should hold up to abuse without breaking.

I created a version using ABS and the following settings:

• 0.2mm layer height

• 2 wall loops

• Sparse infill 20% (probably does not matter)

• No supports (print top facing down)

• Brim: 5mm outer and inner