One of the panels of the AFT OVH is the LE DEVICES panel. A number of LEDs show the status of both the slats and the flaps. I will also make this part myself. I copied the appropriate part from the AutoCAD drawing. I then printed that part twice with a laserprinter to transfer those drawings to the topside (0,5mm polystyrene) and the bottom part (1mm polystyrene).
Then you take a tissue with thinner and wet the back of the paper until the drawing is clearly visible. Then you take some more thinner and rub the drawing with quite some pressure making sure the drawing does not shift. After that you can remove the paper.
As soon as the paper has been removed you will see the drawing has been transfered to the polystyrene. This not only happens with polystyrene but also with other materials (wood, aluminum etc.) and only when using a laserprinter. You’re out of luck if you use an inket. Now give the drawing some time to dry before you continue.
Next you can cut the polystyrene to size. The (thin) top part has to be cut exactly to size, the (thicker) bottom part will have to be cut with a margin so you can later mount it against the back of the panel. Now the holes for the (5mm) leds have to be driled. In the bottom left of the picture you can see the markings and at the bottom right the drilled part.
After that I cut more than enough strips for the walls between the bottom and top panel. I used a width of 1,5cm. There will always be some differences in width due to marking and/or cutting errors. To remove this all the strips are wedged in a vice and filed on one side.
After filing the first side you can turn over the lot and file the other side. If there are strips that are significantly smaller than the rest, it is better to remove them then to file all strip down.
At last you can start with building the contraption. The first strip is cut to size and glued in place with a good polystyrene glue, I use MEK, but any other brand will do. To make sure that the first strips stays in place, I used two squares to prevent it from falling over.