The late Donald Crabtree was the dean of american flintknapping. He underwent heart surgery and prepared a complete surgical kit. His surgeon had to practise, the much sharper lithic edges requiring a different muscular effort. Healing time was greatly reduced with the finer incisions and contemporary glass tools are now used in certain applications, ie opthalmalic repair. I have a fine scar on my left palm below the thumb. I recovered a Folsum point from a Pliestocene mammoth kill site. After millenia it flayed me open faster than my best sharpening efforts on fancy steels to date.