It's a Mysterium
Unexpectedly back on to boardgames stuff today as the replacement box insert arrived for the game Mysterium.
When game manufacturers release expansions there's rarely room in the original box for them unless you bin the moulded 'insert'. Thus there is a whole new business of making replacement inserts that make packing easier, and have more capacity. I've done a few DIY ones in the past but this game was fiddly enough to buy a commercial one.
This company does them in soft plastic 'card' to push out and assemble - the shapes leaving an enigmatic remnant.