Minimize scrap

Hi everybody!! This is my first submission, I made it some time ago in order to save some money. The application's target is to minimize the scrap in a wood wall recovering. I had to buy wood strips to recover a wall in a 45 degrees design, so I had to set the optimal lenght to reduce the scrap. It was very hard to find the matematical model ( combinations, etc) so I used hard force, to choice random groups and to find the minimal. Code is very rough but basically works. It is a very good example using listBoxes I don't need you vote for me, but comments and feed back will be appreciated.