Please, how do I invert what will be engraved on the piece with LightBurn?

[Carlos.Vasques (Carlos de Oliveira Vasques)]

Please, how do I invert what will be engraved on the piece with LightBurn?

[JimNM (James)]

Use the OFFSET tool to create another copy of the object at 0.00 offset to the outside.

Set the layer to FILL.

[jkwilborn (Jack Wilborn)]

If it’s a vector, you can add an outline and use fill…

If it’s an image, there is an negative image in the cut/layer.