I have a piece of test equipment that needs to stay underwater for days. Normally I would use or make a waterproof case with a lid and a gasket.

Instead, I'm wondering if I could print a box, pause the print just before the top face, put the device inside and then print the top face over it. No openings, no nothing, and the device works by induction so it doesn't need to physically connect to anything.

But this would only work if 3D-printed PLA walls are really waterproof. After all, 3D-printed features are kind of a bunch of wires more or less loosely attached to each other, so I wouldn't be surprised if water could leak through under pressure.

Before I spend any time assessing this myself, has anybody tried printing waterproof enclosures?