How much would it approximately cost to start a small smash room?

The furniture, hammers and eye protection would be the least of your costs. Insurance and space rental, assuming you could find a landlord willing to rent their property for such purposes, would be sky high. That’s a lot of potential liability there.

@Darth_Algar Maybe I could open the smash room in the Red Deer university College. In a vacant room am an amedity for college stidents like a climbing wall or food court.

Sure. I bet the college administrators would be thrilled at that proposal.

@Darth_Algar I left a message with residence life.

Well, good luck with that.

Little tip: forget the sledgehammers. Sledgehammers are heavy and cumbersome and not at all easy to use. Go with something lightweight and well balanced. I suggest baseball bats. They’re easy to use for pretty much anyone. Go with the aluminum kind (they tend to be less expensive anyway).