Toy box hinges can be used but the humidity takes its toll. You can also just make a brace type system. I have made some in the past that had a 1/2 inch dowel recessed inside the bottom and top portion of the canopy. A strip of wood or cutting board is cut and 1/2 holes drilled on the ends. You open the canopy then slide the strip onto the dowels to hold it open. Most of the time the canopies are close enough to a wall I don't worry about support and just open and use the wall.
If no wall to support a piece of plastic chord or rubber coated chain can be used but you may have to construct a little "catch" bucket.