an over-lay sheet-
it is a piece of (firm) plastic- you draw the designplacement on the plastic- lay it on the black fabric- then place the pieces underneith it in their place- pin in place- then remove the (placement sheet)you can put line up marks on the plastic- fold the fabric and lightly crease to find the center-
draw the placement guide in a color that will show up on the black--yellow works well