55 formed parallel to and near the top front edge 52 and one of said lateral elements 43 the notched channel 55 extends to and then continues downward into the said lateral element 43 a desired distance said lateral element portion 56 of the notched channel being parallel to the lateral element front edge 53 the frame top portion between the notched channel 55 and top front edge 52 is designated 75 the lateral element portion between the notched channel lateral element portion 56 and the lateral element front edge 53 is designated 76 the frame bottom 41 has a notched channel 57 formed parallel to and near the bottom front edge 51 and the other lateral element 43 u2032 opposite the lateral element containing the notched channel 56 the frame bottom portion between the notched channel 57 and bottom front edge 51 is designated 77 the notched channel 57 extends to and then continues upward into the said lateral element 43 u2032 a desired distance said lateral element portion 58 of the notched channel being parallel to the lateral element front edge 53 the lateral element portion between the notched channel lateral element portion 58 and the lateral element front edge 53 is designated 78 by pressing inward the portions 75 76 77 78 of the frame between the notched channels and the front edges a u201c lock u201d is formed at opposite corners of the frame 40 holding the frame open in a generally rectangular configuration in an alternative embodiment a flat rectangular holding element 60 is pivotally attached along one of the holding element 39 s long sides 61 to one of the lateral elements.