GCLaser has several styles of laser cut shingles. They come in sheets, and can be weathered, a sheet at a time, to give a more random color pattern, when the strips are individually glued in place.
You could also color and weather sheets of paper, and hand cut individual shingles ( cut a strip, across the color streaks, then chop into individual shingle widths ). This isn't all that more difficult than using strips, and produces a true random color pattern.
I've used both, and there are applications where one is better than the other. There's a lot of trim, and fit, using strips, especially between things like windows and doors. In these cases, it's almost easier to use individual shingles.