As the old saying goes, “send your enemies and envelope full of glitter. Send your loved ones an envelope full of stars.”
On that note, the Japan Trend Shop sells envelopes that, once opened, can be held up to a light source to reveal an “astronomically correct depiction of the night sky”. Oh, and you can probably put a letter in there or something, I don’t know.
Packs of these beautiful envelopes run for $83 a set, not including shipping which, them being in Japan an’ all, is probably not going to be cheap. You could buy them directly from the manufacturer themselves where the price is a slightly more reasonable $10, but then you have to figure out how to get them from Japan to your home in… y’know, whatever country you live in. Importers like White Rabbit Express might be helpful on that front.