The challenge of accurate alignment of objects on a sheet of colour photographic paper and masking areas for multiple different exposures in total darkness, demands the assistance of a suitable tool for the job. Commercially available darkroom masking frames are designed perfectly to hold a single sheet of paper flat but have no mechanism for ensuring the precise location of three dimensional objects or re-positioning them for further exposures. I felt this called for a tray design, with shallow sides and removable blocks of different sizes to create the spacing for the commonly available colour print papers I use, 16 x 12 in., 12 x 9.5in and 10 x 8 in. The design I came up with used a sheet of MDF and strips of 10mm thick and 25mm (approximating to 1 inch) wide timber cut to several lengths and painted matt black to minimise reflections. The outer fixed strips have been fixed with adhesive to create a base with internal dimension of 16 x 12 inches. The inner removable strips vary in size from 6 to 12 inches in length, with one 12 inch strip halved lengthwise for the 9.5 inch paper.
One inch is more precisely 25.3mm and allowing for the thickness of two coats of paint (and my very limited woodworking skill-set), the jigsaw of pieces fits together reasonably efficiently. A few small gaps are inevitable however and stray narrow shafts of light should get through unpredictably frequently enough to leave room for serendipity to have an effect. The paintwork needs a few more days to harden and then it will be time to get back in the darkroom to find out how well it works.