What can a fiber laser engrave
When it comes to cutting various Fiber laser machines are more efficient at cutting thin metals. A fiber laser machine can cut thin metals efficiently up to 25mm or 1 inch. After that, fiber lasers start cutting metal less efficiently. You would need high amounts of power, which by the way cost a lot more money, to cut ticker metals above 25mm or 1 inch.
However, fiber lasers cost a lot so you'll need to look into diode-type lasers if you want a cheap laser engraving machine.