Cupholder for locker door

My cups kept falling out of my locker, so i decided to design a cupholder. I think it should fit many standard sized cups. It got the radius of the door, so you might have to alter it to fit yours. Maybe I'll upload a flat one in the future. I fastened it with some double sided tape and it's hanging there for almost a year now. Picture 2 shows it with a phone holder insert, a little add-on, which you'll find on my profile aswell.