### Articles

- ~~[Recycled Plastic Hopper Feeder](https://www.wildaboutbirds.com/recycled-plastic-hopper-feeder)~~
- [Sustainable Bird Feeders Offer Solutions](https://birdschoice.com/blogs/news/sustainable-bird-feeders-offer-solutions-to-attracting-birds-and-minimizing-plastic-waste)

### Tutorials/Guides

- [DIY Plastic Bottle Bird Feeder](https://www.instructables.com/DIY-Plastic-Bottle-Bird-Feeder/)
- [Acrylic Bird Feeder Guide](https://plasticsheetsshop.co.uk/diy/how-to-build-a-bird-feeder/)
- [Low Cost Plastic Extruder for Filament Production](https://www.instructables.com/Low-Cost-Plastic-Extruder-for-Fillament-Production/)

### Papers

- [RepRapable Recyclebot: Open source 3-D printable extruder](https://digitalcommons.mtu.edu/materials_fp/177/)

### YouTube

- [How to make an upcycled bird feeder from a plastic bottle | WWT](https://www.youtube.com/watch?v=Ben9e5p5y8s)

### Open-source Designs

- [RepRapable Recyclebot: Open source 3-D printable extruder](https://reprap.org/wiki/RepRapable_Recyclebot:_Open_source_3-D_printable_extruder_for_converting_plastic_to_3-D_printing_filament)