If you are aware of any existing sets of models that might be useful for teachers of the visually impaired, reply here.
For any teachers who do not know: some of the biggest searchable repositories are
thingiverse.com,
youmagine.com,
3dprint.nih.gov, and
instructables.com.
Like most free resources, you will find the printability and model quality uneven. Check the comments on the models for those that have comments to get a heads-up.