I've never done one with just a square and and X but I've done one that's that shape with a triangle on top. Shaped basically like a house.
Works if you start with the bottom, draw up the right side, the top, down the left side, diagonally up to the right top corner, draw the roof and then diagonally back down from the top left corner to the bottom right corner.
Don't know how to do it without the "roof" part though. :shrug: