Generating Random Pattern from several set curves

Hi, I am interested in creating a random paving pattern from 3-5 different paver sizes of set dimentions. The pavers cannot overlap and each new paver should connect to the midpoint of the previous paver. 

So far I've been able to assign a starting paver and connect to it a randomly selected second paver. However I'm not sure how to continue since now the position of the third, forth etc will depend on the previous ones. I'm also not sure how to make the script continually select a random paver but without accidentally choosing one that would overlap the previous ones.

I was thinking that I would probably need to use a looping system like anemone but I pretty new using grasshopper am having difficulty figuring out the wiring logic. 

Any help would be appreciated.

Thanks :)