For those like me who don't have lateral space near the printer (P1S, P1P, X1), I created a container that only takes up the rear space. Since it's a narrow place to get to, I added some hooks and glued some magnets that help position the container even without looking behind or having to move the printer every time. The 2 magnets near the hooks also help to make the container adhere perfectly to the printer near the slope, thus preventing the poop from getting stuck between the printer and the container itself.
I used 15x2mm magnets because I already had them, but the compartment can also accommodate other similar sizes.

The magnets are inside the container, so you don't scratch the printer every time you take it off and put it back on.
The height of the container does not obstruct the passage of air from the rear grilles.

Since the container is suspended by magnets, various printer feet can be used.

I'm not a good 3D modeler but I hope this model can be useful to others.

I recommend printing with a very light color to easily see its filling level and PETG to ensure greater sturdiness to the small hooks.