Inspired by Bemko, I did a similar support for my portafilter.
It's not the same design, as he didn't share STEP file and I had to make a new one from scratch, but it keeps the same function and design (vaguely).
To be placed under the wooden tray, allows to keep use of the stainless cup, Lelit 58mm portafiler, and even with a magnetic funnel attached to it.
I'm not sure about other brands / models, so I included my portafilter dimensions on the last photo !
The author remixed this model.
Designed to fit Lelit portafilters (and maybe others ?)