(114) Intro to impressioning

You may need to adjust your volume as there is a lot of high-pitched filing noises.
This video hopefully will give you a decent idea of how the process of impressioning a lock works. The essential tools as I showed are a file (I like fine or medium fine pippin profile files for impressioning), key blanks (brass is better than nickle silver or nickle plated), a grip (I like the Framon impressioning handle but cheap vise-gips work just fine) and a magnifier.
With practice you can become quite good at locating marks on the key blank and differentiating between the marks left by pins in different states (at the shearline, binding, or floating).