Step 4: Construct the mechanics.
The workspace is mounted on the old laser diode assembly. Make sure it is flat and level then glue something on that will serve as workspace. I found a piece of 1/4" acrylic that worked out just fine. It made this workspace stable enough but as the laser can shine through it I was not sure if this would be a security hazard or not. Later I found the solution I think works out for the best. I cut a piece of the DVDR metal case to the same size as the acrylic and glued it on. This way it still very stable and you get a workspace that will be tough. One positive side effect is that you can secure whatever you are engraving with small magnets.
For the X axis I found some aluminum profiles in my junk bin but just about anything could be used as long as it is stable. Measure the height you feel will be right for what you want to engrave. I opted for 7.5" long pieces for the support. This would give me a little under 2" clearance.
One important thing, the mounting holes on the assembly are not symmetrical. Be sure to measure the distance from the bottom end of the supports to the linear guides. That way you will be sure to get everything aligned. Where you mount the X axis will be dependent on the laser mounting. The laser should be in the center of the work area when the Y axis is in the middle position. When you mount the axis to the base plate drill a small guide hole for the screws after you made sure that everything is square.
Now you should have the X and Y axis done and square to each other.
The laser mount does not have to be very sophisticated, mine is made from a small piece of plastic sheet and a clip then everything is glued together. Using a clip to hold the laser lets me change the focus point by simply slide the laser up and down. As with all other parts the size is not that important as long as everything is square. There are just one measurement you need to think about here, the laser should be in the center of the work area when the Y and X axis is in the center position.