..I also leave the front and background triangle there, just cut out that middle one. This way when you are piecing you are lining up with the background of both pieces, which is the true edge-- because sometimes no matter how carefully you sew it still gets a little wonky, and that background triangle is there to keep the block straight. There is not that much bulk having the two fabs there. And a snowball corner should be 1/3 of the size of that block...usually anyway.....