“The idea was that a spark of Einstein’s genius would rub off on people using the font,” says Mr. Geisler.

Penmanship experts and readers of Post-it Notes lament the demise of graceful, legible cursive. Computers marginalized it. But now those same devices are opening a world of secondhand handwriting that looks like the real thing.

Today, anyone can write as beautifully as Emily Dickinson—or just dash off an email to the finance department in her filigree style.

And in a twist, technology is allowing fonts to look truly human—that is, slapdash and casual. New fonts can alternate different versions of each letter to make script look vivid. Some fonts seem to smudge a page, or screen, with ink. Others let letters jump erratically off the line, or appear to run out of ink as a quill pen would.