Test plug for K40 Combiner Mount which allowed insertion from the laser cutting bed compartment and test firing to see if the laser exit hole is aligned to the beam. I used a piece of paper over the beam exit hole, did a pencil rubbing to know the edges of the hole, then fired the laser and measured the X and Y distances from the left and bottom of the hole edge to set the beam hole position. I used Customizer to set the X and Y positions, save the STL and check to see if the beam hole is centered correctly. If it was, then a test pulse wouldl make it all the way to the laser head and test material with little to no smoke seen on the Test Plug. I printed in PLA because ABS smoke is toxic.