Here an IRIS CLAMP board for Linhof mount cameras.
 

• An “iris-clamp” is essentially a mechanical, adjustable-aperture clamp/mount that allows mounting a lens (often a “barrel lens” or old brass lens) onto a lens board or view-camera standard — even when the lens lacks a dedicated flange or shutter mount.
• It works by using an adjustable “iris” mechanism (i.e. overlapping leaves or segments) that close concentrically around the lens barrel, clamping it securely; by adjusting the diameter, the clamp can accept lenses of varying barrel diameters.
• In that sense, it is a “universal” solution: instead of being locked into a brand- or mount-specific lens board, the same clamp can hold many different old lenses, making it practical for reuse or adaptation of vintage optics to large format cameras.
• For many old “barrel lenses” — especially those made for plate cameras or early view cameras — manufacturers either omitted a standardised mount or used proprietary lens boards. An iris-clamp provided photographers a retrofit system: they could mount classic lenses on modern (or more standardised) lens boards, or re-use them across different cameras. This made iris clamps especially popular among large-format and view-camera users working with vintage optics.
• The clamps are usually made of metal (sometimes with thin metal “leaves” or segments that form the adjustable ring). Our one is printed plastic. PLEASE CONSIDER IT BEFORE RISKING YOUR LENS TO FALL, SPLAT ON CONCRETE, PULVERIZE, LEAVING YOU BENT  BRASS AND GLASS SHARDS!!!

The first file will be the single retainer version, use it when mounting on those “fatty”Linhof Technika front standards. Second file the 2 retainer version.  All 0.16 PETG-CF and PETG-HF from Bambulab. I tried many, but nothing beats bambu price-quality balance. 
 You will need HARDWARE:

•  1x (2x) M3x16 flat head “cone head” screws
• 2x (4x) M3 bolts
• 2x (4x) M3 washers. One between the set ring and the back plate, one between the set ring and the red gear-knob.
   

Instructions:

• The small red gears have a M3 nuts inside; it's a snug fit and it's put in on a printer pause. I choose to print 4 'cause time is the same and you always lose things, no? 
• The Linhof plate. It's complex, so it's printed in 2 parts and has to be glued back-to-back. There is a (red) frame that's a glue helper. Use imagination, and you will know how to use it.
• The blades: You will print 17, just in case. You will need 16. Discard those that have defects.

• MOUNT ALL BLADES PROGRESSING CLOCKWISE, then put the setting .

  
   

Some things were inspired by others, but all parts were heavily redrawn.