The National 3d Print Society (N3DPS) in the UK is using a modified 3DVerkstan design. It has visor stabilizing hooks on side and gap in front section to allow more breathability and space for PPE equipment underneath the face shield (such as goggles and face mask).
They are in the process of getting the design CE approved and working with a recognized medical company who delivers to NHS. The group just makes the PLA and PETG mount and send to the medical company who sterilize the printed mounts, assemble with the PETG visors and deliver to NHS. Their goal is "providing PPE for our NHS is to avoid face-to-face drop-offs that could compromise health of everyone involved and also make sure that the products are sterilised and sent by an already established medical supplies provider".
STL files (see latest version and README): https://drive.google.com/drive/folders/1mT3Xx7f_WLHilsHBSJy0ZyT5ezwgzqV5
Website (has link to active slack group, slack group has FAQ and standard operating docs):https://national3dprintingsociety.co.uk/medical-am-covid-19/