In this project we use simple rectangles to create fence posts and rails.  The idea is that the fence rails will intersect with the fence post.  The post also needs a rectangle to support the fence panel and keep it upright. 

The improved design will have tenons.  My first attempt at this design was to have the post be double the thickness and have dados cut out to receive the full fence rail.  The issue was that the rail could simply pass through the post and it was hard to assemble.  By creating a tenon, this will provide a shoulder that will stop the rail from sliding through.

To create the tenon, we are simply going to add a rectangle to the end of the rail.  Just note the size of the tenon so that you can use it for the dados because they must match.

The next step is to create the dados to receive the rails.  This is a little tricky because you need to account for the kerf of the laser.  My machine is the D1 with a 5W laser, which has a kerf of .08mm.  To account for this we simply double the kerf, which is the cut on the top and bottom of the rectangle, then subtract that from the dimensions of the rectangle. (I've done this in the file, so you can just run it, but I wanted you to know how to calculate this so you can adjust if needed)

All processing in the project is a cut, so set up is easy.  Just be sure to edit the settings if you have a laser other than the D1 with a 5W laser.

The last step is to assemble the parts using a little bit of wood glue.  be careful to just put a little on as it will squish out the sides.