We are remodeling a master bath, and want to create a raised border in the shower area using the same tiles as the rest of the room. The entire shower will be covered in 6x6 tiles with a 3 foot relief section of 4x4s placed on the diagonal. I would like the border of the section and the 4x4 section to be raised about 1/4 of an inch to create some visual interest and textural relief in the shower area. How can I do this? Thanks.