Canadian electronics designer AE Innovations has created a helmet that makes it sound like you're talking in "droidspeak." Yes, that's R2D2's and BB8's beeping, whirring droid language. The helmet doesn't actually "translate" anything: its throat mic merely detects when you're speaking and prompts the device to emit a series of beeps and clicks that sound like they came straight out of the movies.
The best way to use it, though, is to have another friend wear one, as well. That way, you can chat through the helmets like they're walkie talkies. Nobody else will hear what you two are actually saying -- it also has earphones -- because to the people around you, you're communicating in high-pitched beeps and whirring sounds. Hey, it might be against C3PO's programming to impersonate deities, but it's not against ours to impersonate droids.
AE Innovations posted his development process, the components/audio files/images he used and his schematics on Hackster. If you don't have the right knowledge and skillset, it will be impossible to recreate. But if you do, then enjoy making a couple to outgeek everyone else on Star Wars Day.