We started out thinking of a graber design but dropped it. We did have a way to flip the boxes either right side up or upside down. It was very simple. We took to pads and placed them on bearings and found a spot on the box that you had to hit. Using stops and a set hieght. Once you lifted it would used gravity to flip the boxes to whatever side you wanted to stack them. We dropped that design because we wanted to throw the boxes. We can use our thrower to stack and orient the boxes to lid side up. It is a very simple design. We have two Forks that we use to hit the boxes and flip them or we slip under on side of boxes that are on their sides and lift and they flip up right. We can stack up to 5 high. I hope we post pictures but if you want to see it go here.
http://www.archergeeks1022.org/imagelibrary/default.asp
and click on heavy weight