make a knock box for your spent espresso pucks for next to nothing.
you will need:
a container (I got this tin from a pound shop, but you can use an old coffee tin or something and make this even cheaper)
a bit of wooden dowel, just slightly longer than the diameter of your tin.
Step 1: Shape the Dowel to Fit
use a file or saw to shape a notch into the dowel so it slips into the tin snugly. Then file the sides to match the outer shape of the tin so you can get the lid back on.
Step 2: That's It.
now go make some coffee!
I plan to add some tape to the dowel to soften the blows from the portafilter , and also I'll be adding a hinge to the lid, but it's not necessary.