I recall now that I made my portafilter bottomless by attacking it with a hole saw, in case you can't find one. The threaded hole for the spout makes a perfect pilot hole.
This is also a perfectly valid option!
@Tijmen started
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I recall now that I made my portafilter bottomless by attacking it with a hole saw, in case you can't find one. The threaded hole for the spout makes a perfect pilot hole.