Alright so, say I want to set up a marketplace where only accepted traders are allowed in. I set up a runestone/sign outside saying if they wish to join the Market, they would have to leave contact details, of some sort. Leaving their hearth secret on a runestone isn't that great.
Another scenario, is conversing with strangers. You come across someone in the wild with something you don't have. You leave them a runestone you're interested. They leave a runestone in response. You leave a runestone. They leave-... You get the idea. It gets cluttery, messy and is a grand waste of boulders and such.
So, what I propose is a constructable Mailbox, which uses parchment for mail. Anybody can access the mailbox, unless you throw a lock'n'bolt on it. You can then grab the written-on parchment from them, and write a reply below, till you run out of lines, which cannot be "overwritten", leading to another parchment being in requirement.
Of course, throwing a lock'n'bolt on means that the stranger also can't read anything you put in, so instead, he could "post" you his location, HS, etc.
Or alternatively, you could pin a parchment to your palisade, and... I digress. You get the idea.
It's only a half-thought one, but that's what the Critique and Ideas board is for


