I had 4 controllers, and my dog managed to destroy two of the backs, so I went to creating as close to a replica of the back as I could. Printed with .25mm base layer and .15 layer height afterwards. Used PLA, ABS should work, but minor scaling may be needed for shrinkage.
.15mm layer height, .25mm base
Outlined old back using fine tipped pencil. Took basic measurements using vernier calipers, and used the outline sketch with a protractor and compass to find the angles and rounds.