Heyho
I have recently constructed a portafilter holder for my Superkop espresso machine. And I am super happy with it!
I have now also integrated a height-adjustable handle holder so that the stand also works for other portafilters of the same size.
The inner diameter of the holder is 68 mm.
I have not yet done the work to design this part for other diameters. But that would also be feasible in the future.
In addition to the 2 pressure parts you need 2 x M4 x 25 mm cylinder head screws.