For a fun project I always wanted to make a led badge (like those on EE conferences or deacon 😄). This is my first prototype of this kind of a device, I based it on addressable led's and an STM32 micro. I did not have much of a choice because of world wide shortage of electronics parts... As a fun feature I imagined it could communicate with another badges to synchronously play a light animation and If it wasn't enough the colors would be controlled by an iPhone app. For this I equipped every device with nrf24l01 radio modules, and to add a communication with phone one module had a HM-10 module. Unfortunately this decision had a little backfire - I could not use the CR2032 style batteries because of excessive current consumptions, so I settled on AAA's and this made the whole device bigger than I wanted it to be. But it was a lot of fun designing it.