Cool idea! Your granddaughter will lover her "One of a kind" quilt. This gives me an idea. We were in a quilt shop the other day and DH pointed out some 3 Stooges fabric. Something like this would be perfect for it.
For those who would love to make a quilt like this, there is nothing wrong with doing a half-square triangle on those corners. BTW, RedHawk, you did a beautiful job on those miters!