9mm to 13mm plug with slatted air opening

I made this design because I started having humidity problems in the ant farm. Too much humid air was accumulating and wasn't evacuating properly, so I needed something that would truly ventilate without the risk of ants escaping.

I tried several mesh solutions, but they either closed up during printing or didn't provide enough airflow. In the end, I opted for this system of solid bars in a single direction, which has worked much better for me.

The bars have a separation of approximately 0.38–0.40 mm, which in my case has been enough to prevent escapes even with small ants, while still allowing plenty of air to pass through. Furthermore, being solid bars and not a fine mesh, they are much more resistant and there are no problems with them deforming or fusing during printing.

The plug is designed for 9 mm holes, with an 8.8 mm entry, and has a small press-fit system with rings to keep it securely in place. In my case, it fits firmly and doesn't move or fall out, but if it's too tight, it can be adjusted by sanding a bit.

The top part is wider to improve ventilation and airflow, and the entire structure is designed so that there are no strange gaps at the edges where ants could slip through.

I designed and printed it in PLA+ with a 0.4 mm nozzle, without supports, and it works well with 0.12–0.16 mm layers. I printed it at a slow speed.

Since using this design, I have noticed better ventilation and less humidity accumulation inside the ant farm, with no escape problems.