This slide rule was recently donated to the MIT Museum by Elliot Billing. It is a specially modified 4081-3 such that a blind person could use it. The following is Elliot's description of its history:
I worked for the American Foundation for the Blind as an Engineer for 10+ years. The Braille slide rule was given to me during that time. The Foundation had a long history of designing devices for the Blind. Often this involved adding Braille or tactile markings to existing devices. They had a complete machine shop and electronics lab. The K&E 4081-3 Braille Slide Rule was either developed at the Foundation or in collaboration with K&E. It dates from 1952-1955. I have no idea how many were produced. It's tactile markings are small rivets and the guide is a thin wire. The craftsmanship is superb. I suspect it was useful but difficult to use for those even familiar with Braille due to the spacing of the rivets at the ends of the scales.