There is no badge for this activity. It is just for fun! Try sleeping int your Den overnight!
When your leaders were about the same age as the Beavers and they were stuck indoors for any reason, they would make a den.
Sometimes we did this using chairs and blankets, sometimes we did this in our bedrooms using whatever was at hand. And sometimes we used cardboard boxes.
Why not help your Beaver’s make their own den and post pictures of them on your sections closed Beaver Facebook group if they have one. You leader may make a montage of photos if your whole colony gets involved!