Most slats are 4 feet long by 2.75 inches wide by 3/4 thick,( unless you have a 5 foot bench, in which case they would be 5 feet long), Home Depot or your local lumber yard would have these...at some places they could cut them for you. All you might have to do fancy would be to round off the front edge of the slat that goes at the front of the seat.
A table saw and some dimensional lumber (redwood is perfect, cedar is good too) that is slightly larger than whats needed will do the trick.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.