A quick design I just drew :)

It's more of a “holder” than a "stopper", since the magnets aren't that strong when blocked by filament. But it holds the door at a postion, which was my main focus :)

Uses one 7x20mm magnet with a (included) 1,5x20mm plate. Just pause the print and insert it. There is also a shim to get the perfect distance. It's only 0,4mm thick. Use doublesided tape to stick it to the door and floor. If you need help with anything, just ask! :)

I used this magnet: https://www.amazon.de/dp/B08K39Q1DL?psc=1&ref=ppx_yo2ov_dt_b_product_details

Let me know, if something doesn't fit!