A scriber is a hand tool used to mark lines on log pieces, prior to carving. The scriber has two level bubbles to keep you hold it straight up and down. The process of using a scriber is called scribing and is just part of the process of marking out a log to be shaped. Pencils are used to make scribe lines which are thin clear lines.

Underscribing

The idea is to keep those logs fitting tight over time. The problem is the logs drying and shrinking. The corners need to be prevented from getting loose. The idea is to make the notches extra tight at first, knowing that the corner notches will shrink. This is what is known as underscribing.