This is a handy little tray designed to hold all the different parts of a 1/10th scale RC Motor while you're working on, it holds the rotor in position and helps to spread the parts out so they don't all just get magnetised to the rotor.
Handy also handy when you're cleaning your motor you can put the rotor in the middle and place the shims for each side in the compartment on the correct end of the rotor, so you know which way they go back on.
The author hasn't provided the model origin yet.