build a saving platform

i want to build a system that allows anybody in the world to save money over a given period of time. it is simple, create an account, and start loading money in it, you cannot remove the money until the fund time reaches. it works with paypal. create an account, login or signup, create a saving box(how long will the box be sealed, and start loading it up, withdraw money straight to your bank account or paypal ) i will send you the explanation.