A customer of mine has recently done a fantastic job of stretching my very wide painting himself. In the process he saved himself a lot of money on the stretching costs!
He bought rounded-edge timber from the d.i.y. shop Wickes and then screwed the frame together with 7cm screws. He was pleased that the resulting frame was nice and strong, square and straight.
The customer also purchased corner brackets from a local hardware shop. The holes in the corner brackets mean that the stretched picture is able to hang on the wall by simply balancing on screws, with the screw heads keeping the canvas in place.
It was also handy that the customer already owned a staple gun and he told me that he liked the type of canvas material I used when it came to him stretching the canvas over his wooden frame.
Overall the customer took his time and did a careful job and the result is absolutely fantastic!