I do not have a design board, I just used the floor and stood on a chair to get a better perspective lol, actually it may sound silly but as I was making a bed quilt I used a combimation of floor and bed, that way I could see how it was going to look as it came together laying the quilt down on a bed since that was what it was designed for. I also used the method which artists use of squinting at the arrangment to help with tonal value, it really is worth doing that to achieve contrasts etc.
Gal