"Autism Conference" reminds me of this,Autism conferences have been using these for years, though usually on a lanyard as far more visible.
A lot of people are, understandably, quite concerned about the heavy social demands of being in a large group for several days. There is no requirement to socialise at all, and there will be no implicit or explicit disapproval of those who choose not to interact with others. There is coloured badge system for indicating whether you would like to socialise or not.
No initiation Red Please do not initiate any interaction with me.
Prior Permission Yellow Please do not initiate unless I have already given you permission to approach me on a yellow badge.
Please initiate Green I would like to socialise, but I have difficulty initiating.
Please initiate with me. Neutral White (or no badge)I am able to regulate my own interaction.