Ph.D. candidates in Mechanical Engineering, Pranay Jain and Anshul Singhal from the Massachusetts Institute of Technology, have invented Squirrel Devices to address this problem. Caliper tools were imprinted with Braille measurements so students with blind and low-vision (BLV) disability can effectively obtain dimensions and sizes of continuous geometrical shapes. This instrument is targeted for students at K-12 or secondary levels so they can keep up with their other peers.
The tactile caliper is precise to 1/16 of an inch and is four times finer than current rulers. One of these calipers cost between $18 to $29.95. Other units of measurements such as centimeters are currently unavailable in Squirrel Devices and the maximum length it can measure is 12 inches or less. Take a look at this video for a demonstration.