As a slate-roofing contractor, I bend most of my own drip-edge flashing. For small jobs or for bending metal on site, I use a portable sheet-metal brake just like those available at tool-rental centers for around $70 a day. Sometimes called a siding brake or an aluminum brake, this tool can be used for cutting and bending flashing for windows and doors, and for cladding for exterior soffits and fascias. It also can be used for any number of small projects that require bent light-gauge sheet metal or vinyl. When renting a brake, make sure a slitter is included for cutting sheets to width.
Bending a drip edge is a good project to demonstrate how to use a brake. A drip edge requires several different kinds of bends, from a slight kickout to a full fold.
I prefer 16-oz. or 20-oz. sheet-copper flashing rather than aluminum or painted galvanized steel. Copper is expensive, but it lasts longer and looks better than any other flashing choice.
When you’re using a brake, it’s a good idea to use a piece of scrap for a mock-up to ensure that all the bends can be made in sequence. For drip-edge flashing, I cut a 6-in.-wide piece. I fold the hem and kickout first, then work my way back. I wear gloves to protect my fingers and also to prevent fingerprints that would tarnish the copper. While the measurements here create a standard drip edge, a brake allows me to customize the profile if I need to.