creating a spiral with RelItem

Hi,

i have a little problem. i want to get a spiral drawn at the walls of a room - actually four spirals, one starting at every corner of the room.

like this:

initially i thought this would be very simple but right now i just don't get it done. first i tried with the shift list component but that wasn't working out like i hoped. now im trying to use the RelItem component but i just can't handle it the right way.

help needed, please