[MrForbes]

Another approach if you can' find the aluminum channel you need, is to make it from sheet. All you need is to find some place that has a good (heavy) sheet metal brake. Also it helps to use a soft grade of aluminum, and to practice bending first on a smaller piece. And if you first bend another strip of metal, and put it on the fingers of the brake, then you can bend a larger radius and it will be stronger.