I would do that task in Illustrator.
But anyway, I place those kind of templates in InDesign or Illustrator in a Layer which is set to not print and it is locked..
I work in other layers, so I can see where it will be at the end.
Place the PDF on a layer of its own at the very bottom of your layer stack. Make sure the PDF is placed at 100% - its original size.
Lock this layer so you cannot accidentally move it. Set it to non-printing - this template is FPO and so its contents should definitely *not* appear in the PDF that you are going to send back. (You may want to do test prints on your local printer, and then of course you want to include the template so you can see what you are doing. There is an option to specifically include non-printing layers.)
It's (kind of) okay to draw your own design immediately on top of the template, but I imagine you'll have a hard time getting it right, because every side rotates a bit. In this case I'd probably design every side upright and only rotate them into position when the design is final. Of course this is going to be a challenge when the design is to wrap over multiple sides (or entirely around ...) but then again, life ain't no fun without the odd challenge.
Thanks for your comments! I will give it a try
It certainly is a very interesting job - I can't recall if I ever had one like this.
Keep in mind what Willi says: depending on what you are planning to do with it, parts may be better designed in Illustrator and then placed into InDesign. (Or do the entire job in Illustrator, but personally I trust on InDesign for final assemblies.)
I agree, something new for me too
I think I will design each side in Illustrator and mount it togheter in InDesign. Hopefully I will manage to make the design flow without any problems