I got the idea from another bird feeder and designed my own to fit a 2 liter plastic cold drink bottle.
To easily fill it I also made a screw on funnel for the bottle.
I printed all in ABS
bottle-bird-feeder.STL | 1.7MB | |
bottle-bird-feeder_perch.STL | 803.6KB | |
bottle-funnel.STL | 693.1KB |