This is my first share of something that I made. I'm new to CAD and learning, so be gentle :) Since I print in a basement, even with windows, I was concerned about printed with ABS. After adding the excellent https://www.printables.com/model/272525-bentobox-v20-carbon-filter-for-bambu-lab-x1c-enclo by thrutheframe and https://makerworld.com/en/models/116660#profileId-125407 by Imaginarydave, it still smelled. I spotted https://makerworld.com/en/models/65403#profileId-68729 by albertpasquale where he did a magnetic cover for the poop door with goal of decreasing fumes. However, it was a flush/flat surface on the inside. I remembered that the external chute on thrutheframe's https://makerworld.com/en/models/20194#profileId-85098 was nicely fitted within the Bambu X1C's poop output external opening. This give me the idea. I did try at first to modify thrutheframe's design, but I'm not good enough to make Fusion360 do what I want. So I measured his design for ideas and made this one from scratch. If anyone wants to improve it, go ahead :) We all make each other better.

-I used 4x 6x3mm magnets. Very tight fit on PLA, no glue needed. I printed it with TPU in the pictures, which I think will make a better seal. I used CA glue on the TPU for magnets. It might be worth adding extra magnets for a tighter fit, but since it isn't really ever air tight, this might be overkill, I just stuck to 4.

-I made the magnet hole depth 3.1mm with the idea that it would pull the TPU into the Bambu X1C back and make a better seal. I'm not sure the validity of this, but it made sense.

-I FILLETED the corners to 4mm in Fusion, this seemed to work and give the best fit to the Bambu's opening.

-The above printed with OVERTURE TPU High Speed Filament 1.75mm Flexible 95A TPU.

Thoughts

-I actually wonder if a softer TPU would work better, or more magnets, or maybe decreasing infill to make it LESS strong and more flexible. I printed with the Bambu default GENERIC TPU profile for filament, and I tried the eSUN downloadable profiles for the TPU-95A for the Process. I haven't noticed much of a difference between the Bambu Generic TPU profile and the eSun TPU profile, but I was previously happy with the eSun profile for PETG I used, so I tried it.

-There is a perforated air holes next to the cover. The cover could probably be extended easily to cover this, but I'm not sure if that is harmful in some way.