There is an Austrian company that now makes a pen that vibrates when you make a writing mistake.
According to the company, "Electronics integrated into the Lernstift enable the device to recognize
a wide variety of writing movements and alert the writer by vibrating
when a mistake has been made. Specifically, two functions are available
on the pen: Calligraphy Mode, which points out flaws of form and
legibility, and Orthography Mode, which focuses on detecting spelling
and grammatical errors."
Here's the part I like best.
“Lernstift’s subtle, yet unmistakable vibrating alert lets us know instantly and sensorially when a mistake was made."
Seems like it would be great technology for condoms.