My WDT tool is machined from Delrin in black or white, not 3D printed. It comes pre-installed with (9) 0.22mm needles. From my experience, needles of larger diameter moves the coffee around rather than fluffing and breaking clumps. The larger needles will create more clumps, opposite of what a WDT tool is meant to do.
Needles are replaceable and a full extra set is included.