Smart backpacks for riders are nothing new. We have covered a bunch of them that have been funded on Kickstarter in the past. Arduibag is a smart backpack that you can build on your own. It displays a flashing arrow to indicate to drivers which direction you want to turn. You can also display a “STOP” message when you need to.
Arduibag can display time, temperature, and other data. Trying this open source project can be a great learning experience. More info is available here.