Pilot4514, The first thing that came to my mind, would be to cut a 3.5 inch freezer paper template. Lay it on point on the striped fabric and cut it out.
When you lay it horizontal, the stripes will be on the diagonal. Word of caution, if you do this the 4 edges are on the bias, and they stretch out of shape
very easily. Hope this helps. If you have other factors you need to consider post the way they are going to be used. HelenW

How do you cut fabric with vertical lines on it to 3.5” blocks with the stripes being on the diagonal?