So , I ' m tired and I ' m not going to explain this well . Having said that if you are not to purest about it you could think about building up rather than cutting down with a router . It would be much less work to start out with a piece of plywood and then laminate layers where you want the raised parts to be . Basically think of how you would build this with lego . You will have a much easier time cutting thin , straight pieces of wood to glue on to a board than starting with a thicker board and cutting voids out of it . Routers like to jump around a lot , cause tearout , and as someone else mentioned , are somewhat dangerous . If I were doing this , especially if it was my first project I would do it that way .