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Generally speaking you want the grounding (bare or green insulated conductor) to be mechanically bonded to the fixture as a chassis ground so any metal parts of the fixture if they become energized will cause the the circuit to short out and trip the over current protection (circuit breaker or fuse ). When fixtures are designed they need to meet Underwriter Laboratories (or another equipment listing agencies) standards before an electrician will wire one and install it, otherwise using non listed parts could present legal issues if a fire were to start. Since you are designing this fixture yourself I strongly suggest you ground any metallic parts of your design, and after you have produced the finish product do extensive testing to make sure the light functions, does not pull an excessive amount of amperage based on wattage of the bulbs and most importantly is thermally safe so it or other objects around it (like decorative coverings) do not catch fire.
I'm all for your enterprising initiative, just be wary, you do not want to bring a potential fire hazard into the reception hall. UL listings and the National Electric Code are electrical contractors safety net when installing equipment, please use extreme caution when designing your own circuits/ luminaries.