I needed some ventilations to some exterior boxes, but didn't wanted it to allow entering water, so I designed these ventilations/breather pieces.

Here you will find two different designs, one to be fitted at the top, another one to be fitted at the face or sides of the cabinets.

Each breather is designed in two parts, one that will be put from the inside and another one that will be put from the outside. If you really want to avoid ANY water entering, you should apply a thin coat of silicone.

I've been using this, printed in PLA, in extensive rain for the last couple of months without any problem. The interior of the box gets well ventilated (to avoid mould growing), and it's completely dry on the inside.

Solidworks project is provided, in case you want to easily modify it.