I was looking for inspiration when I stumbled across this U-Box from Stanford Graduate School of Education. It's an interesting project with some great features, I didn't calibrate things correctly so my box is a little wobbly and loose, the assembly clips are definitely clever. The files are shared in multiple formats on their site but as ever... (svg here)
The lid rotates round 270 degrees on these large disks, the lids can fold down flat against the side of the box which is a very neat feature.
An extra shim of material is affixed to the underside of the lid so that it fills the gap when the lid is closed. In the closed position the lid clips into place with a slight friction fit.
Here is one of the assembly clips, it springs into place once into the gap and a second spring on the top pulls it out of the gap so it pulls tight.