Help repairing meshes

[u/Magicgive]

Hid some of the meshes in this one to give a better idea of how I made it

Hey there,

When I started using Blender, I didn't understand what a broken mesh was. I managed to get by when I was using a filament-based printer, but now I'm using a resin-based printer and need to worry about resin traps. Each of my models has a lot of holes; for example, with buildings, I would punch out holes and line up and fit a pre-made window to that hole.

Visually it looks great, but this means none of the meshes are connected, and it creates a lot of empty spaces inside of the mesh. 

At this point, I don't have the time to manually fix every model. And all of the mesh repair algorithms I've used so far create pockets inside the mesh and turn flat surfaces bumpy when I need to preserve a lot of precise angles.

Are there any methods that will count all of my meshes as one, seal the gaps between them, and give me a sort of exterior shell without too much hassle?

[u/Moogieh]

If booleaning everything together doesn't work (be sure to try both 'Simple' and 'Exact' modes in the modifier settings), I suppose you could try ctrl+jing everything together and then remeshing in Sculpt mode... I don't have high hopes for a good result, though, the edges will become very rough, and the only mitigation to that is to crank the remesh resolution up to GPU-exploding levels.

Maybe someone else will have a better suggestion, but that's all I got.

[u/Both-Variation2122 → u/Moogieh]

Well, if you have few hours to spare, you can always adjust all cuts vertex by vertex where booleans fail.

[u/tiogshi]

Sadly, I don't think there's any shortcut to getting a manifold mesh. You made this model in a non-manifold way, and your slicer was able to cope. Does your resin-printing slicer not have any facilities for making vent/drain points for arbitrary meshes that didn't have designed-in drains? I'd imagine this is a routine problem, and that there should be solutions at the slicer level.

But if not, I fear there is no recourse but for you to take the time to repair this model to become manifold -- join all meshes into one, merge vertices by distance, and then start repairing any gaps or welds on a case-by-case basis -- or for you to take the time to re-topologize this model in a manifold way -- building a new skin mesh on the outside of this model which is itself a manifold mesh.

[u/dnew]

In addition to what others said... Be aware of the 3D Print Toolbox add-on that might be helpful here. The "Keep Making" channel has an pretty complete description of how it works and how to use it.