if you have many old mouse. you can do it for new model.
up to your idea. but i have one choice for you.
This is box for put pen or anything that you can put it.
2.keep out all eletornic
3.cut plastic in side mouse
*** but not cut socket.
4.install front and cover
sorry i'm not good english but i want show my idea only
if you like i'm try to show next time.