This definitely exist, It is called Precious Plastic, it is a project started by Dave Hakkens. It is a collection of Open-Source machines designed for recylcing and reusing thermoplastics.
There are phenomenal collections of videos for introduction into plastic recycling and machine building.
So far they already developed 4 DIY machines:
- Shredder machine,
Plastic waste is shredded into flakes which will be used in the other machines to create new things. You can select the output size of these flakes by changing the sieve inside the machine to create different patterns and processes.
- Extrusion Machine
Extrusion is a continuous process where plastic flakes are inserted into the hopper and extruded into a line of plastic. These lines can be used to make new raw materials such as 3d printing filament, make granulated plastic, spun around a mold, or used in your own new and creative ways.
- Injection Machine
Plastic flakes are heated and injected into a mold. It’s a relatively quick process which is well suited for creating small objects repeatedly. You can make the molds completely yourself by using CNC mills or lathes, or by simply welding them.
- Compression Machine
Plastic is heated inside the oven and slowly pressed into a mold with a carjack. Well suited for making large and more solid objects, the oven itself is also a great machine for prototyping and making plastic tests with.
If you wanna more information about the 4 machines of even want to build one, everything is explained in details with video here.