I urgently needed transport boxes for my Skywatcher HEQ5 Pro mount and my Baader Travel Companion.
I decided to cushion the box for the mount with 2-component PU foam. For the APO, I still want to get cut foam, but until then, I was able to make good use of the remaining PU foam there.
I chose Festool boxes due to their specific dimensions.
Here is a short series of pictures. If you have any questions, feel free to ask in the comments.