For my new Bambu X1C, I've designed a small HEPA filter cover which is slapped on the back of the printer, and held on using a bunch of magnets. I just installed it yesterday and have not tested it, but it looks cool at least. This is going to be a temporary solution for my printer though, since I will eventually add a duct system similar to my current enclosure setup.
The plan for the next iteration will be to run a duct from the outlet on the back of the X1C, with a booster fan (6038 12V) inline, which will vent out a doggie door (through a printed cover). The booster fan will use a 4 wire PWM fan, and I'm planning to design a remote PWM controller, with a potentiometer to control the speed. I think the booster fan will be needed, since there is going to be several feet of hose, and the small fan on the back of the printer won't cut it. I'm also considering a small circular filter in the booster fan housing, since I prefer to filter the air before sending it outside. I'm still waiting on parts to finalize that design, but I was able to use some of the earlier models from my current setup, which helped speed things along a bit. If the fan has enough power, then I think the newer design should be improved over what I'm using now, and more modular as well.
Below are some pics of the inline booster fan (with a filter), and the last pic is the coupler which will connect the hose to the printer. Although they look complete, I need the parts to finalize the models.