This project requires off-white fabric that does not glow under a black light. You'll need to start with a square piece that is at least 10 inches wider than your table's diameter. A small, round table is ideal.
Source: Martha Stewart Living, October 2008
Fold square in half to form a rectangle; press with an iron on medium heat. Fold in half to form a small square; press. Position so that center of original square is at top left. Fold bottom-left corner to top-right corner, forming a triangle; press. Fold top-right corner down to triangle's longest side, forming a narrower triangle; press.
Place top point of triangle at the center of table, letting the rest hang over the edge. A few inches below the overhang, cut an inward arc (see left) through all fabric layers with scissors.
Unfold fabric. Lay atop a paper-covered surface (this will help absorb the marker, which will bleed slightly). Using a quilting ruler and a black-light-reactive invisible marker, trace folds extending from the center to the tips of the scalloped edges.
Outline edge of tablecloth with marker. Draw bowed lines, parallel to edge, between folds. Let dry 20 minutes.