These are parts to add a top tray to keep things out of the ice and water if you want. The half tray can be slid side to side to access things underneath or you can use two of them. The full tray has a finger slot so it can be lifted up or pulled out to access the main compartment.
I used a gorilla glue and clamped the bottom and top parts together overnight. I have only used the half tray a few times but so far so good. I did find the half tray a little small for some things so the full tray was the answer to that but I have not tested it yet.
The author marked this model as their own original creation.