Scribers are, in a sense, idiot-proof. Hazards include scratching your skin or piercing your skin. It is advised that you do not throw a scriber or run with a scriber, as they are sharp enough and long enough to pierce through your skin and into your internal cavity or organs. Never use a scriber as a center punch.

Dividers are used for marking circles on metal, or for marking out linear distances between two points. They can be used with a ruler to create a parallel line next to another line. As with scribers, do not throw dividers or run with them. Always keep dividers clean and lubricated.

Odd-leg dividers are used to scribe a parallel line to an edge on a piece of metal or sheet metal. It is important to always keep the scriber point sharp and to keep the odd-leg dividers lubricated. Do not throw or bend the legs of the odd-leg dividers as this will throw them out of calibration.

The center punch is called this because it creates a big dimple in metal when used which will be the center point for drilling a hole. The dimple created is large enough for the drill bit to center itself. Whereas a dot punch creates a very small dimple, large enough only for marking purposes and for a divider leg to catch in it to scribe circles. Do not strike either of these two punches with excessive force, and only strike them once to create the desired dimple. 

Steel rules are used to mark straight lines, also called linear distances. They come in lengths of 150mm, 300mm, 600mm, 1000mm, 1500mm, 2000mm, all the way up to 6000mm. It is important not to bend them, or to bash them like swords. Bending them causes them to be less accurate and bashing and denting the edge will prevent them from being straight and true. The edges are sharp, and a steel rule can cut through the skin easily. Use it with caution.

Most engineer's squares are made from tool steel, which does not rust easily but is less hard than stainless steel. They consist of a thin-bladed section and a fat base section. The base section is wider so that it can catch onto the edges of the metal you are working on easily. An engineer's square has been calibrated to be exactly 90°, and as such any damage to it will through this accuracy off. Do not use a square as a hammer. Do not bend the thin-bladed section of the square.

A protractor allows you to mark out different angles on sheet metal or metal. As with all marking-out equipment, the protractor is fragile if used incorrectly. If it is over-tightened on the pivot, the pivot will break out of the body. Do not bend or throw a protractor.