Test Strip Omega (& Omega Zero Calorie)

You thought the Ultimate Darkroom Test Strip Maker was… well, ultimate. But you were wrong. Because I famously don't know when to stop innovating.

Presenting the newer, bigger, better, more polished, Test Strip Omega (and fun-sized sidekick, Test Strip Omega Zero Calorie).

Test Strip Omega allows for extremely simple creation of localized test strips when making enlargements in the darkroom. Print the same area of projected negative at different exposures onto 3 evenly-spaced strips on a single 4x5" sheet of paper (1/4 of a standard 8x10), and revel in how easy it is to directly compare the results.

Budgetary metabolism not what it used to be? Test Strip Omega Zero Calorie is even more economical in its use of expensive silver gelatin paper, using a 2.25x4" sheet (1/8 of a standard 8x10), and allowing for 4 different exposures.

You're only a day of 3D printing and a laundry list of odd hardware purchases away from producing test strips that would make Chris Woodhouse and Ralph Lambrecht ask for your autograph. Particularly if you use the included stop-based timing PDF attached to this Printable for locating your perfect base exposure.

Print Considerations

An opaque, neutral-colored, and non-reflective filament is ideal for Test Strip Omega. I am using Overture Matte Black PLA with great success.

Most parts can be printed with a standard 4 top/bottom layers, 3 walls, and 25% rectilinear infill. The Housing Top and Shuttle Top should be printed with at least 30% cubic infill, to decrease the chances of accidental light transmission from 0.2% to 0.0%.

Be aware of the print orientation, which is not natively correct for all parts - specifically the Shuttle Cap should be flipped to ensure you're not trying for a 90° overhang.

All objects are optimized for printing with 0.4mm walls and 0.2mm layer height.

Bill of Materials

• (1x) Each of the STL files (for either Test Strip Omega or Test Strip Omega Zero Calorie)
• (4x) M5x8 brass heat set inserts
• (4x) M5 screws of your preferred height (to make sure Test Strip Omega holds the paper at the same height as your easel does. I like low profile heads since my easels sit low to the baseboard.
• (4x) Rubber bumpers (These ones do an extremely good job of preventing Test Strip Omega from sliding around during use)
• (2x) M3x16mm screws
• (8x) M3x8mm countersunk screws
• (7x) M3x4mm countersunk screws (this kit has plenty of all the sizes you need)
• (12x) 6x3mm cylindrical neodymium magnets (or 14x for the Zero Calorie version)
• A bit of superglue or epoxy to set the magnets in place

Assembly and Usage Instructions

Remix Culture

Fusion360 files have also been provided under a Creative Commons license so you can remix and create a Test Strip Omega for any of the odd sizes you want to use. I know you make triangular test strips, Todd. You weirdo.

Share it far and wide, just don't try to profit from my design. The last thing we need is more barriers to entry for new darkroom printers.