Assemble bankers box and use hot glue to secure the handles down. A binder clip will hold it until dry.
One of the 12×12 egg crate tiles will fit in the back of the box perfectly. Put the other three tiles on the sides and inside top. No need for padding on the bottom. Use a sharpie to mark where to trim and use scissors to cut down.
A few dabs of hot glue on the corners will do fine for securing to sides.
That’s it! This is a great project for your room mom or PTA for larger numbers.
I made 6 for under $50. They’re not the cheapest, but if you reuse bankers boxes that you can find and maybe source out some used egg crate material you could do them for pennies.
This one on Amazon is $36 with Prime- for just ONE!