Hey, how can i make a reservation to a hotel in Las Vegas without putting my credit card anywhere and pay cash when i get there?

Basically, you cannot make a reservation without a CC. The will only give reservations to people who they think are able to pay, and the only easy way to prove ability to pay is a CC - basically, some bank somewhere trusts you enough to give you a CC, so the hotels will go along with it. When you get there, you will be able to pay cash, though you may have some minor problems because it breaks the system - checkout clerks don't want to get out of their lazy habits,