I’ve never used a 3d printer before but want to get one. I have a bit experience in blender but not too much. My question is: How do you model for a 3d print? For example, if I want to print a hollow cylinder, I go into blender, create cylinder and delete the side faces. If I print this, the walls will be pretty thin. Do I have to make them bigger manually? and if I do so (extrude and scale) does my slicer (cura) automatically fill in the solid part?
That is a weird take. File format is completely irrelevant here. 3D printers usually only accept G-code files, or something similar, which is unrelated to the file format used for the model. You can also easily convert pretty much anything to something your slicer will accept.