Funny,
have discussed this many times before ! For tiles to be "random" it involves not thinking about it too much and sticking them on as they come ! But if you do then you can end up with colour blocks and running out of one colour and having too many of another left over.
My best advice is to discuss in depth with customer prior to start. Ask them how they perceive random to look. some customers may not like to see a block of more than three together.
truly random would mean tipping all the tiles on the floor, mixing them up then shutting your eyes and picking up which came next.
In reality you still have to think about the "random" pattern, which is quite a contradiction of terms. :dizzy2::dizzy2::dizzy2::dizzy2::dizzy2: