Taiwanese company STC is working with Olympus Taiwan to design a screw-in filter holder for Olympus 7-14mm f2.8 PRO. The holder takes an 105mm filter. Currently their CPL shows slight vignetting, but the newly designed ND filter could possibly avoid that. They’re still not sure if they should make an ND4, ND8, ND16…maybe your readers can help advise on this ;) They also say it’s possible (and easier) to make one for Pana 7-14mm. Based on the comments, this will be available at the end of next month at least in Taiwan and Hong Kong. Not sure if it will be available elsewhere, though. See here:
https://www.facebook.com/STCsense/posts/1004034246360892
Thanks B.!