Catarina and I made this funnel design in www.openscad.org. This particular funnel is 50mm wide with a 2mm hole. We made it because we needed to pour some liquids. :)

Note: the inside overhangs actually killed the print. we need to adjust the height of the funnel for a better angle. Cool effect though!

Update: we used the funnel to pour acetone knowing that it would dissolve the threads on the inside. it completely sealed all the cracks and now its a great little funnel.