Hi Pilou,

They were separated objects. As you say, both would work but it's easier to modify the pattern as separated items.

I use the CurveLengthV2 script to copy/paste the width/height from destination object to rectangular base object.
From Petr's MoI page:
http://kyticka.webzdarma.cz/3d/moi/
http://plugmoi.voila.net/index.htm

PS. If you wanted to manufacture this object, it would be better to Boolean union the pattern. :)