gollytwo

I make mine the same width and length as a strip in the quilt
e.g., if it's a rail fence with finished 1 1/2"X 5" strips - that's what I use in the border
I don't use a foundation and I don't usually do light-dark.
I use the same fabrics as are in the quilt top.

I don't use a piano key border if there are no strips in the quilt itself.
Except when I made a music quilt and then I did a black and white, alternating.