I strongly suggest not using public photocopy or xerox machines for your immigration documents or visa approval copies. Example: Documents like passport biometric pages, and US visa approval copies like i-797 contain important identification information and can be easy to misuse. Almost all copier machines have a hard disk that stores your documents before printing. This storage is not deleted automatically and can be accessed by the machine owner. It is always better to scan your documents using your smartphone and then upload them to your Google account cloud storage. You can print them once you have access to an office printer or invest in a good all-in-one printer.