I made a new magnetic funnel for my portafilters. I own a Gaggia Classic and an open basket portafilta with an IMS B702TH26.5M basket, but i think this design should fit E61 portafilters as well (please let me know!). The Outer Diameter is about 70mm for my portafilter. My 58mm tamper fits right trough the funnel if you want to tamp with the funnel on the portafilter.

I used pretty standard 10x2.7mm Magnets (5pcs) so the funnel stays in place. There also is a press-fit version if you don't want to use magnets.
The Print i uploaded was made with 6 wall perimeters but you can use pretty much any Filament/Settings i think. Printed in DasFilament PLA.

Have fun printing & drinking espresso without any coffee grind spill.

P.S. I have provided .step .f3d for easy editing/remixing.