Membership card or lapel pin?
Imagine the police stop you for some minor reason and discover your picks. Legally there is a heavy onus on you to show you are not carrying them for some illegal purpose. A card would be helpful in showing that you have a legitimate reason to have the picks. Of course if you are inside someone's house or business, forget it.
There would have to be some minimum level of participation to obtain such a card - perhaps a minimum of 50 posts that display in the opinion of admin, a knowledge of the field etc. And the card would have to be phrased in such a way that Keypicking was not vouching for the members' bone fides.
Finally, the card could be a source of income or at least cover its own cost for the site.
???????
(Here is Lock Picking 101's lapel pin, which I am sure you have seen.)