Further proof that the universe of coffee gizmos and knickknacks is infinite and, for some of us, remains irresistible. Behold, the WDT tool.
WDT stands for Weiss Distribution Technique, which is a fancy way of saying gently stir ground coffee in the portafilter before tamping, to break up clumps and even out the density in the puck. The promised benefit is a reduction in channeling (water finding empty space within the ground coffee during brewing), which should lead to more consistent quality and higher extraction. The technique was developed by a PhD computer scientist and home coffee enthusiast, John Weiss.
I recently got one, and tried it for the first time today. To be honest, I think this is something where it will be impossible to find significant impact. If nothing else it will mean a little more confidence as a home barista, and I found it oddly soothing to stir the grounds gently, which felt soft and fluffy.