But such a 'pixie dust' already exists - and Lee Spievack's ten perfectly formed fingers are living proof.
Mr Spievack sliced almost half an inch off the top of one of his fingers in the propeller of a model plane.
Four weeks later - and following liberal sprinklings of an experimental powder made from pig's bladder - his finger had regrown to its original length.
Before and after: After cutting off the tip, Lee Spievack's finger was back to normal in one month
After four months, it looked like any other finger, complete with "great feeling", a finger nail and fingerprint.
"The second time I put it on I could already see growth," said Mr Spievack, 69. "Each day it was up further.