How can I go about closing this one-sided mesh without having artifacts? I’m a beginner and have been trying to find a solution for a while now.
There is nothing really to “close” on that mesh. It’s mostly an open surface with no logical holes to close. Trying to “close” a mesh that is that open will not produce great results.
What you are looking to do is extrude some thickness to your surface. You can do this with ZModeler, or with Mesh Extracts. You can also extrude with the transpose functions if you are capable of masking a portion, but that doesn’t work in this scenario.
It would probably be easier to simply recreate the geometry with the desired thickness to begin with. The jagged edges on that mesh make it a poor candidate to do much with.