Not terribly hard, depending on the route you want to take. For me it was harder because I used bolts to mount (looks really clean), but normally you can use some 3M #4010 (or similar) to mount the window. I also used some C (also called U) channel for the cut. For tools, I just use a good old ruler and a jigsaw. I just don't have a steady hand (or a good place to do the cutting).