I'm almost finished with step #4 of Bonnie's mystery, which are string triangles (produced by cutting string squares in half). I'm happy with how all the reds are working together. With 1900-era being my guide, I used all kinds of reds from double-pinks to light burgundy.
Step #5 is completely done. Wings were added to the HST units from step #3 to make triangle-shaped units, shown below. These took several hours, sewn over a few days. I don't understand how some of the quilters get these steps done in one day!
My cat Tiger found the quilt pieces in no time flat!