DIY 19th century Bluetooth handset

What? Don't look at us like that. It's true. Kind of. Sure, you're required to have some sort of late 19th-century handset lying around, as well as a Jabra 250 you don't mind cutting up and cannibalizing for parts. But if you don't want to drop the money on someone else's version, and have both too much free time and a lot of room in your bag for a gadget that'll get lots of (positive and negative) attention, then a late 19th-century Bluetooth handset might be the hack for you!