This is a parametric slide box generator.
Enter the external length, width,height, and the material width.
Be careful the dimension will be recalculated : show the real dimensions in the echo windows. And adjust.....
Change the value of "view" to 1.
Save as "svg" and import in your laser cutter software manager. You can add text and picture to engrave.
Glue as shown picture "sbfirst". Don't forget the 2 "brown" internal pieces !
Wipe the excess of glue.
Glue the red upper part. Beware of the excess of glue.
Eventually use abrasive paper to adjust the sliding part.
You can make every box you need !