Feet Base for the SainSmart LC-40 Laser and File to make a grid for easier repositioning of stock. Print 2 as is and 2 mirrored ones, if you have problems with “elefant feet”.

Glue them on a piece of plywood or similar. That will fix your laser position. Now laser your Grid.

You maybe have to adjust the grid a bit, as it depends on your actual set max X and Y distance. I was not able to upload the LightBurn file directly, but the svg should work fine.