How do I accurately select half of a symmetrical mesh? I have this mesh that is probably nearly 100% symmetrical on both sides. I want to easily select half of the mesh, in order to hide it to have easy access to its inside. My object is directly aligned with the origin, so would there be like a Hot-key to be able to select any parts of a mesh in one side of the axis?
You can select everything relative to the last selected (active) vertex.


Select the middle vertex
Access the menu: Select -> Side of Active.(Which has options regarding which side/axis).