Note and Wish has a really interesting tutorial on how letters were folded and sealed in the Regency period. It's a surprisingly complicated procedure that nests the flaps from opposite sides of the letter to create a stable seal. Just the thing if you're looking to create sealed missives for your tabletop RPG players.
There's also the historical practice of "letter locking", sealing letters in such a way as to make it obvious if they've been opened.
ReplyDeletehttps://www.youtube.com/@Letterlocking/videos
Further links in:
ReplyDeletehttps://en.wikipedia.org/wiki/Letterlocking