This is a filter holder to mount 100mm wide filter screens (like Lee, Haida, Cokin etc.) to the Panasonic 7-14mm f4 super wideangle lens.
You need 2 rubber rings (like o-rings) to control friction of the filter in the holder.
To mount the holder smooth on the lens, stick 2 or 4 felt pads (or velvet pads) to the grooves on the inner side of the tube.
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/panasonic-7-14mm-f4-filter-holder/ for more information.