Parts rendered inside-out if camera is flipped horizontally

Any idea how to put a stud texture on a meshpart? I’ve never used meshes before. I pulled a stud texture from the toolbox, and entered it into the TextureId property of the MeshPart, but it doesn’t seem to do anything. I am not sure if this is because the texture is not loaded, or because the viewportframe can’t display textures, or something else.

Here is a screenshot of what I currently have:
image

Another issue I’ve encountered is that setting DoubleSided is limited to plugins and command line. This is fine for the time being though.