This is a remix of the portafilter holder designed by teky929rr for the Gaggia Classic Pro espresso machine (base model found on Thingiverse).
The original design has been changed to be more stable, and includes a wider top clip and a series of recesses to hold 6x2mm magnets. Add as many magnets as needed, and depending on printer tolerances, superglue may be needed to secure the magnets.
It is best printed on its side, angled about 30 degrees, using tree supports, and with the top clip rotated 90 degrees from its intended use, such that the layer lines end up vertical when installed.
Edit: Added a mirrored version for use on the left side of the machine.
The author remixed this model.