Project Core is "a stepping-up technology implementation grant directed by the Center for Literacy and Disability Studies at UNC Chapel Hill" that has created 3D printable files for assisting in communication.
They currently have STL files for "Go", "Like", and "Not" available here - http://www.project-core.com/3d-symbols/
As the designs are not final they prefer not to post the files on Thingiverse yet, however, they kindly share their work in progress from their website.
Posting in the event this may be of interest to those in the group.
Our department has been using the project core 3D prints for a few months now and a lot of the OT's and classroom teachers are really on board and working together on implementation. I think I have printed of about 5+ set and there has been a really great response so far. I really like how solid and unfussy these prints come out!