It would depend on how wide you want your border. Try half the size of your 3D blocks and measure the total length of quilts. Try a square of paper that size and fit it along the quilt. If you have 8 inch blocks and 2 inch borders, then you would need 8 four inch blocks on the side to make a four inch border all around. Just guessing at the size from the look of the picture. it is a lovely quilt.