13th Jan 2019 - Updated Version Available! Thing 3353329. The new version works with both screw and cork wine bottles, improves drainage and reduces the need for supports.
There are many designs for bottle based bird feeders but the majority use plastic soda/coke style bottles. I was looking for something a bit more refined and decided to create my own design for screw top wine bottles. The majority of screw tops are based on the Stelvin wine closure which appears to have an M30 thread or at least the M30 produced by Fusion 360 fits like a glove.
The design as a feeder part together with a top section. One top section has holes not parallel with the bottom. The two parts being intended to be linked using paracord or tent guy-rope cord. The other top section has holes aligned with the bottom so the two sections can be joined with threaded rod. The holes are 6mm.
As it would be a pain to dribble bird seed into the opening of a wine bottle, I've also included a screw-on funnel. Possibly overkill but the opening of our normal funnel would not allow the seed to flow properly.
The final STL of the feeder section is slightly different from the other images - I removed a domed section that was intended to spread the seed but just made it jam up. Also increased the areas joining the threaded section to the base.
Feeder section 30% infill.
3 Top and bottom layers.
1mm drainage holes are included but may require opening depending on the accuracy of your printer. A Dremel or small drill would be fine or possibly a heated needle.
Top section 20% infill.
Supports from print bed for the hole 'wings' only.
Funnel settings not that important but will need supports from print bed to the hole at the top of the threaded area.
3 shells and top/bottom layers.
I printed in HTPLA (because the silver looks quite cool) but ABS or PETG would be OK. Don't know how standard PLA would hold up being left outside for any length of time.