For $25 we can buy a little USB device that has 6 audio outputs. They intend them as front/back, left/right, and center/bass; this is called 5.1 audio. They provide three standard 3.5mm headphone jacks for plugging in the speakers.

Suppose instead we plugged in 3 cheap pairs of headphones giving us 6 speakers. I know we can drive 6 independent channels of audio out to the speakers at the same time. If we can make the sound loud enough a user should be able to feel the tiny headphone speaker vibrating with their finger. We could arrange the 6 speakers like the keys on a Braille embosser. You "feel" the dots with the same fingers you would use to press the keys. Or we could arrange them like a Braille cell if desired. By playing low-frequency sounds on the 6 speakers we can make the vibrate. So to display a letter we play sounds to the appropriate dots. Only those speakers will vibrate.

A super cheap commodity Braille display you can assemble from parts easily bought anywhere...