This app was mentioned in 4 comments, with an average of 1.00 upvote
Do you have an android phone? Try Case Simulator 2
I play with Case Simulator 2 got an inventory of about 15k lol and it cost me $0.
The app I think is called case simulator 2?
Yup, here's a GPlay link - https://play.google.com/store/apps/details?id=com.SmokedStudios.CSim2&hl=en_GB