I used to build this filter holder in vacuum cast technology. Since the lens went out of production I can't afford to maintain the mold any further. The filter holder is therefore available as 3D SLS print.
It isn't that smooth and pitch black as the original but it's still available.
You need a rubber band (or an o-ring) to put friction on the filters. You should glue felt pads inside the barrel to prevent scratching the lens shade.
Please note: Shapeways delivers printed parts only. You will need felt pads and o-rings to turn this part into a working filter holder.
See
https://helge-suess.com/hardware-en/zuiko-7-14mm-f4-filter-holder/ for more information.