Everything beginns with the enclosure. If you decide to drill the enclosure by yourself, use this template:
As an alternativ a drawing of the dimensions:
Depending on the accuracy of your printer you have to modify the template. I use the scaling function of the printer driver. (If your printer tampers the picture horizontal and vertikal differently, you need to open the template with inkscape and correct it there)
This is what it looks like after drilling:
Before painting grind the enclosure with steel wool. The particals of the wool can be washed away under water.
The enclosure seems to be clean but if you check it with grain alcohol and a paper towel you will see that there’s still much dirt on it.
Just before priming the enclosure I clean it again. This time with break cleaner, so it’s absolutly free from grease.