I'm not sure you have the volume to justify a stamping die. Tooling costs in China should be no less than 2k for a good quality stamping die. Piece price will be fairly low, but you will have to roll in your tooling costs to that price since the volume is low.
To me, CNC machine aluminum shouldn't be too expensive, especially if the tolerance are forgiving. Hardest features are the square pockets, but you can be creative with that, or find inserts that allow you to make a less-square hole. I have not seen a back to your rendering, but I am assuming it is relatively flat. That part just begs to be CNC machined out of 6061.
I am concerned of the glass temperature of 3D printed PC. Is it going to deform with the heat of the lights in the summer in the desert Southwest? I would feel better about machined or injection molded PC, but the glass temperature is still a concern. The glass temperature is the temperature at which the material starts to transition from a solid to a soft solid (jello) and can be formed. For most 3D printed plastics, it is usually 60-80 deg C. I have seen a couple of materials that break the 100 deg C barrier, but not many and they are expensive and difficult to print.
