When the object you wish to engrave has a circumference, the method of choice is typically rotary engraving, especially if you wish to engrave the object on more than one side. It is usually far easier to rotate the object on a spindle than it is to rotate the engraving equipment around the object. Most rotary engraving falls into one of two broad camps. One is mechanical rotary engraving, in which a pattern is cut or pressed into an object by physical contact with a tool. The other is laser rotary engraving where no engraving tool comes in contact with the object, just the laser beam.
There are many factors to consider when choosing a method of rotary engraving. Chief among these are the material to be engraved, the required precision of the marking, production speed, and the shape of the mark. In general, laser is faster, more precise, and lets you engrave a much wider variety of marks than is possible with the contact methods.