The question is how to attach the pieces to the backing fabric.

It doesn't leave it sticky when you pull it off.
I was told to glue the seam allowance to the back of the interfacing, leaving it in, and sew the whole thing on to the block.

But I've never done it before, not have i done much hand sewing, but I can do blanket stitch, and it's rustic looking so it might be ok.