Saw cut losses, multiple boards?
There seems to be something missing in the definition of this problem.
Must saw cut losses be considered? Are we dealing with enough pieces to require the use of more than one board?
If all the little pieces can be cut from a single board, the wastage is constant, unless you have to consider saw cut losses. You get the total area of the pieces and subtract from the area of the board. The difference is the wastage. In this case, you do not have an optimization problem.
Does the solution require knowing the width of a saw cut? For example, you cannot cut a 24 by 36 piece of plywood into four 12 by 18 pieces. You will end up with 11.875 by 17.875 pieces because a saw cut loses about .125 inches. In this situation, you have to know the width of a saw cut.
If the solution requires the use of more than one board, you have an optimization problem. In this case, it is easier to think of it as a packing problem. Imagine fitting 2D objects into 2D boxes. I once worked on a 3D version of this problem involving optimal packing of freight cars.
As of 30-40 years ago, a solution for the general 3D problem was not known. In practice, some simple algorithms could be used to obtain pretty good solutions which were acceptable in practice.
The 2D problem might be more amenable to a solution than the 3D problem I worked on.
