How are you going to make a "sheet of end grain"? :huh:
I think his frame in this method was simply an alignment tool to corral all the blocks together while creating the design.>>>> cut your stock into 1x1x1" cubes, say maple and red heart or a dyed cherry would work well. then make 4 frame rails that are 1" tall by 3/4" thick by however long.
Not really a good idea. An end grain cutting board is going to want to expand and contract in length and width with changes in humidity and moisture. A solid wood frame around an end grain field will restrict the movement of the field. This will result in the field being damaged or destroyed and/or the glue joint holding the frame being forced apart.
Trying to glue a lot of individual pieces of wood will be almost impossible. As I said in my above response, the way end grain boards are made is to glue strips together, flip them over 90 degrees, crosscut them to the thickness you want the board to be and then glue the strips together into the board.