I have made three Bird Feeder things - the latest being version 4: http://www.thingiverse.com/thing:359618 - but filling them when attached to the window is always a bit messy.
I have tried using a standard funnel and also a newspaper rolled up into a funnel shape and although this is a little bit more flexible I always end up spilling bird seed onto the floor.
This thing is nothing more than a funnel with an angled spout but it makes the job so much easier.
EDIT: Although it didn't need it as I printed and used the first version of the funnel which is shown in the photographs without any problems, I had another play with my CAD application and reworked the design to have thicker walls (1.6mm rather than 1.2mm on the first version) and a smoother "bend". The STL for the second version is FUNNEL2.STL. Just to stress - the first version works perfectly well, I just wanted to make it more elegant perhaps :-)
Funnel.stl | 14.5KB | |
Funnel2.stl | 28.2KB |