It takes a bit of manual dexterity (I guess the name comes from that) and some hand-eye coordination as well as a good straight edge. I tape down a large steel square for that. I have been using the same one for 35 years, and it has not failed me yet.
But it's not easy, so most will just pass it by.
|AT-6 Harvard by jarud|
from Trainer aircraft
|Monarch butterflies winter roost at Pismo Beach by cjf2|
from Safety in Numbers (Nature)