I stretch my own canvases and like to use a pre gessoed 407gsm cotton duck canvas, which arrives as an enormous roll. The process starts with assembling stretcher bars, which push together with a little persuasion and brute force to square them up. The canvas is cut on the floor in the hall as that is the largest open space in the house. I lay the frames on the opened roll to work out how best to cut out the pieces. Once cut the canvas is stretched onto the frames in the studio. There is a strict routine to stretching to get a good tight surface, I take care of the corners so they are neat and unobtrusive