I have seen a lot of tutorials on how to make pinwheel blocks from half square triangles from four 5'' charm squares (two pairs), but couldn't find one for a pinwheel block from only two 5'' charm squares. I have a lot of 5'' charm packs that have only one of each print, and if I wanted a block to only have two prints in it, I'd have to do it with 2 charm packs. So, I wracked my brain and figured out a way to make a smaller pinwheel block from just 2 charm squares. This finishes to just under 6'' when I sew it, but you might be able to get a full 6'' block with a scant 1/4'' seam allowance. I like to square mine to 5 1/2'' though (to get a 5'' finished block) so use a full 1/4'' seam allowance. I think one of the best parts is that it's not necessary to do any marking on the fabric like in the larger pinwheel blocks where you mark a diagonal line and sew 1/4'' on each side of that diagonal line. No marking necessary on this technique! Anyhow, here is my very first tutorial!
EDIT: Yes, the block edges end up on the bias. But, with such a small block, they really are not an issue. I did not have to starch my blocks to keep them from stretching. If it was a larger block, I might consider starching though to keep them under control.