This is an espresso dosing cup.  I designed it for my Mazzer Mini grinder.  I made it tall enough to minimize the mess and with a nub on the bottom to keep it from sliding off the portafilter holder.  The cup rim is sized for a standard 58 mm portafilter.  I printed it in translucent PLA but will likely reprint in black to match the other black parts on the grinder.