The finest 3D printed screen I can make.

Two ideas occurred to me to allow me to make the holes even smaller.

I was previously creating a 3D model of a mesh where the horizontal lines were connected to the vertical ones, but it occurred to me that this is unnecessary. The slicer simply cuts horizontal planes out of the 3D models, so like since I do 0.2 mm layers, it starts at 0.1 mm and cuts that plane out of the 3D model, then goes to 0.3 mm, then to 0.5 mm. What the shape looks like between these heights is irrelevant. Thus, it's not actually necessary to connect the horizontal lines to the vertical lines and, by not connecting them, the shape only needs vertices at the two ends of each line, which makes it a lot easier to deal with in Blender.

The second idea was that I could create two layers of it and offset them so that the spaces in one layer were covered by the lines in the other. Thus, even though the lines of plastic are 0.5 mm lines with 0.5 mm of space between them, since the 0.5 mm spaces are blocked, the actual spaces become the 0.2 mm between layers.

I made this because I want to introduce the things I've been referring to as "aquarium pests" into my main aquarium. I don't think there's any real risk in doing so since, as they reproduce, the little ones are so insanely little that I think they'll be eaten by the fish. I also wouldn't mind if there were a chance that, if my ghost shrimp ever decide to reproduce, that there's a chance some might survive to become bigger, but they are very small when they're born and so if they're to not be sucked up in the filter then it needs to have a very fine mesh and a very large area so that the water flow rate in any particular area is low. This mesh is about 12 cm square.

I'm also thinking I can use the larger box that it will need to attach to to hold peat moss which is supposed to lower my water hardness.

Of course, now that I'm thinking about this more, I'm not sure what purpose the filter is going to serve with this super-fine mesh preventing even the tiniest things from entering the filter. Maybe I made it too fine.

The box the screen attaches to. The intake tube goes under another screen to try to let it draw water through the whole area since the peat moss isn't very conductive of water.

The lid bolts on top. Making stuff that bolts together is satisfying.

...and the intake tube almost fits in the top. I attempted to copy the hole size from the last intake thing I made, but I made an 11.1 mm radius hole when I needed a 9.1 mm radius. I'm just going to print an adapter if I don't just fix it with hot glue.

I was thinking about how the fine screen effectively will do the filtering before the water even gets into it, and that made me think that I should make something that I just stick a paper towel on and it sucks everything through that. No small animals are going to get through a paper towel. I suppose I can just put a paper towel on this by just making something to slip over top of it to hold it in place.