I recently had cause to engrave a bunch of wooden bingo balls for a project. I bought some cheap 40mm balls from the internets and stained them with some indian rosewood strain. The numbers themselves were engraved and outlined on both sides of the balls to make them easy to read from multiple angles. The balls were held loosely in place under the laser head, lightburn really helped with this project because it allowed me to set the reference point as the centre of the image. I could align the red dot to the very middle of the ball and know that the number would be centrally aligned.