Black lines through every part after importing GLTF I'm new to blender and need some advice. 
I have imported a GLTF file of the render/animation I am trying to make (robot for a competition, want to show off capabilities in animation), and when I import the file, it ends up looking like this. Originally the model is a .step file, but I used the CadExchange program to make it compatible with blender. The lines do not show up in the rendered images or animations, but they make it really hard to work with, especially selecting items to parent to each other, which I need to do a lot of. Any help with this is appreciated, thank you!
Those are empties (what you get from doing Add &gt; Empty &gt; Plain Axes in the 3D Viewport). They are created for glTF nodes that have no mesh, no camera, aren't a bone, etc.
You can try running this script from the Text Editor to hopefully clean up some of them that aren't necessary. Save beforehand.
import bpy
while True:
    dead = [ob for ob in bpy.data.objects if ob.data is None and not ob.children]
    if not dead: break
    for ob in dead:
        bpy.data.objects.remove(ob, do_unlink=True)