Richard Clarkson designed this "survival" kit that should, in theory, help you go trough demonstration or civic unrest. It is probably more of artistic / design type of a project, with probably limited real world application.
I couldn't find published STL files.
Now, it could be just an art project, but I watched TV report on Brasilian demonstrations against world soccer cup. When the police shoots tear gas, people ran and go to buy similar homemade antacid spray dispensers to neutralize the tear gas from small street vendors.+ who fallow the demonstration with their sales carts.
Project homepage:
