Another cool tip.  Make it adjustable so that it will alter to cot and then to a single bed size.  That way when you daughter makes the move to a single bed bed, you do not need a rail.  It helps to keep them there and stops rolling off.  Also when your travelling to stay at someone's home, it takes up far less space than a travel cot.  Have safety sleep, will travel!   (Well, thats providing that your host has a spare single bed to use!)

JH