The phrase "to form a cross" means to create a shape that looks like the letter "X" or the Christian cross symbol when two things intersect or cross each other. Full definition
On a work space, overlap 2 strips of zucchini and then overlap 2 additional strips on top of and across the first 2 strips, forming a cross shape. (the-chew-recipes.com)
Rhodium plated sterling silver forms a cross adorned with leafy vines that blossom into 3 precious (novica.com)
Rhodium plated sterling silver forms a cross adorned with leafy vines that blossom into 3 cabochon (novica.com)