Chapel Perilous has taken its toll on me and indeed, my cosmic trigger finger is broken. For readers not familiar with Chapel Perilous I will give Robert Anton Wilson's definition of that god forsaken place. In researching occult conspiracies, one eventually faces a crossroad of mythic proportions (called Chapel Perilous in the trade).
Keep wood chisels razor sharp for building cabinet doors. A good set of chisels helps clean up and fine tune mortises and tenons or remove a bit of wood anywhere you need to, such as the ends of panel grooves in door frames. A chisel set and mallet are essential woodworking tools.
You need to be able to read a measuring tape and calculate volume and other geometrical metrics. When cutting a door frame, you need to accurately measure the width and height of the frame to ensure the door fits correctly. Self-employed carpenters also use math skills in preparing estimates on projects.