A box of handmade things โ letters you unfold, flowers that need water, a tape that actually plays. Nothing in here was bought.
Type it, or switch to handwriting and drag your finger across the paper like a pen. Choose a wax seal โ and if the letter is meant for one particular day, seal it shut until then. Once it is folded you can decorate the envelope with stickers.
Real flowers, pulled from Wikipedia as you go. Pluck a leaf off if you want, pick a stem up by its photo and drag it where it should sit, then tie the bunch and stand it in water. Whoever opens the box can pull the blooms about and they will sway back.
Open-licensed music from Wikimedia Commons, Openverse and the Internet Archive โ or paste in a YouTube link. Fill up Side A, and say why in the liner notes. Whoever opens the box gets a tape deck and a turntable to play it on.
Pasting a link always works. Search goes through public mirrors, which are sometimes down โ if nothing comes back, paste the link instead.
Side A is empty โ find something above.
This records your actual microphone, here in the browser. Nothing leaves the page until you build the box โ then the recording travels inside it, on its own little cassette. Say the thing you would not write down.
Your own photographs, printed as polaroids. Write on the white strip under each one โ that caption is what someone reads when they pick the photo up and turn it over.
Tap a sticker to drop it on the lid, then drag it where you want it. Hover over one in the tray to save it as a PNG and keep it. Draw your own in the grid above.
A plain canvas and a brush, the way drawing programs used to be. Pick a colour and a size, draw badly on purpose, then keep it as a PNG or turn it into a sticker.
Every box that has been built, and the link that opens it.
An index card for the recipe you would want them to still have in twenty years. Handwriting on the title line, method underneath.
Small sealed notes, each labelled for the moment it is meant to be opened in. Open when you miss me. Open when you cannot sleep. They stay shut until then.