We've been holding onto another special thing that'll be unique to #39C3... were we'll unofficially challenge 
@milliways to a challenge coin challenge!
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RE: https://hachyderm.io/@dotmeow/115757407650716286
My coin collection is gonna grow. I definitely need to figure out how to store challenge coins at some point in the future, because I'm too much of a mess to not lose them in my flat. 
@mcfly do you have any suggestions? :'D