Create the Base
Using foam board, cut out two simple triangular tree shapes. Cut one of the shapes in half lengthwise. Attach the smaller shapes to the larger shape with a glue gun on opposite sides. Using foam board or cardboard, cut several triangles to fit in the corners like shelves, securing with hot glue. Note: we had our tree break through the glass. You can make this as a standalone tree by gluing the two simple tree shapes together.