When I unpacked and turned on the printer for the first time, I didn't know about this phenomenon. In fact, I knew exactly 0 about the 3D printing process.
In the English-speaking internet, these things are called "Poops". Literally - poop, dung, etc. On Ukrainian resources, they are referred to in various ways (pups, poops, rubbish, snails, etc.).
The name was obviously given due to the similar shape and essence (waste that is expelled from the back of the printer). So what is it?
What are Poops in 3D printing?
These are small clumps or strands of plastic that the printer extrudes to clean itself before a new print.
A simple example. I am changing the spool of filament from one color to another. The printer extrudes some amount of filament (in the form of poops). If you look closely, you can see that the new filament has extruded remnants of the previous plastic.
This means that the new print will not be spoiled by remnants of the previous plastic (of a different color). When printing with multiple colors - your printer will "poop" quite a lot, ahem ^_^
In fact, these clumps of plastic can be collected. There are several videos on YouTube discussing the problem of plastic generation (waste) and the possibility of recycling it.
So, you can collect this waste in a separate bag/box (to prevent dust and other dirt from contaminating the material). When a large volume is collected, you can move on to the recycling question.
Note
You cannot place the printer tightly against the wall (with the back wall), because there is a hole through which the printer expels its poops ^_^ and a fan for cooling.
On Makerworld, by searching for Poops + Printer Model, you will find a bunch of different interesting solutions. For example, there is a basket like this that allows the plastic spool to slide off to the side, which allows you to move the printer closer to the wall and clean up faster.
https://makerworld.com/en/models/677183-poop-chute-basket
I have filament behind, so I use a regular box for the poops (so they don't lie around everywhere).
BambuLab P1S Poops
I couldn't find more info on why exactly so much plastic is extruded by the BambuLab P1S before each print. Most likely, it's for cleaning and all that. But I stumbled upon a thread on Reddit where people are modifying G-code to turn off the generation of poops (but there are some very specific cases).
