[1] Referring to the drawing, make layer-structure units by gluing together pieces of balsa wood of varying thickness. This will allow the dimensions in the depth direction to be understood in each layer. The lens' optical axis and film (CCD) surface will be the reference points so draw lines to each position. [2] Fit the balsa wood to each block. For thicker parts, glue several pieces of balsa wood together. [3] Write in the dimensions for each of the parts and then cut them out. Pictured here are the parts lined up in the order that they will be layered.