For CFC Origami's September 2025 prompt, "The Seed Package":
Imagine yourself on a train to Shanghai. You just bought some nuts in their shell, and it feels like snack time. Alas! Where are you going to put the shells? You have no bag, but you do have 15 cm kami. Of course.
So, here is your challenge. Design a small foldable bag for anything as small as nut shells, seeds, or small money you wish to keep together.
It must have an easy way to open and close, and a formidable lock, to prevent it from spilling its contents in your bag. And, of course, the bigger the volume, the better it is!
This model has 2 modes: a wastebin mode, where you can drop in your items, and a packet mode, which locks the items securely for transport (or disposal.) It's best used with small, fairly flat objects like paperclips, coins, or seeds.
Wastebin mode: a simple box that you can drop the items into.
Packet mode: double locked to prevent items from getting loose.
This guide uses 15cm kami (per the prompt) which is double sided (multi-colored pattern front and single-colored pattern back.)
Pre-fold the creases for easy construction.
1
Fold horizontally and vertically into thirds. This is easily managed with a ruler or template guide, but once you get used to the proportions, you can potentially do this by eye.
2
Fold the diagonals. These will collapse to create the base of the wastebin/packet.
3a
Fold the edges down to create reference marks.
3b
Fold the edges down to the reference marks. This will allow the model to lock in both wastebin and packet mode.
4
Fold additional diagonals. These will allow easy collapsing from wastebin mode to packet mode.
Following the first 3 precreases will create the wastebin.
Fold along the thirds and its connected diagonal to create the top left box corner.
Fold up along the diagonal and pull the right side in to create the top right corner.
Repeat these steps on the other side to create the other two corners (1).
Repeat these steps on the other side to create the other two corners (2).
Fold down the top edge in order to lock the sides of the box.
You can now fill the bin (up to about a quarter of its height to still allow for packet collapse.)
Follow the fourth precrease to collapse the wastebin into a packet.
Carefully unfold the top edge (the sides will become unlocked, so try to keep them relatively in place.)
Follow the creases from step 4 to carefully collapse the sides in a pinwheel fashion to create a relatively flat packet.
Following the edges from step 3, purl the top layers inward in a second pinwheel lock.
You may need to partially unfold the first arm in order to tuck in the fourth arm of the inner pinwheel, which locks the packet.
Unfold the two layers of locks to open the packet. You can fold down the top edge again to reinforce the wastebin walls.
Additional views of the little wastebin.
Top-down view of the model in wastebin and packet modes (both partially filled with paperclips.)
Side view of the model in wastebin and packet modes.