No, not at all. Thaught i explained enough, not a man of many words ☺. But i ll try to tell more, if anything isnt clear just say. Also im dutch, so excuse my english.

I used isolationplates u can buy at any hardwearstore, online even.
I used roofmate as the first layer of background because its sturdier and i had still had some at home. Then i bought some styrofoam plates cause its much cheaper, like 6 euros for 10 plates. The roofmate would be 70 euros for the same amount.
I cut the plates up in smaller pieces, max 50cm cause i got a trim at the top of the tank. On some plates i used another layer of styrofoam to overlap the cuts and to create a bit more dimension.
For the inlet i used wiringtubes where u can later connect the hoses to and drilled holes in them for an more even and low current.
I then coverd it up with styrofoam and made some holes in that.
For the outlet i build 2 sump like chambers 1 with a piece cut out of the top for the skimmer and 1 with a hole near the bottom to collect waste. I ll post some pics later to show how i coverd the holes.
I also made a cave using several layers of styrofoam and created some platforms the same way.
Then i used tileglue to create a more natural look. And thats the step im currently at.