Measure your box, then make sure the foam fits in it as securely as you can. For this lid portion, I cut two blocks in half then used 3 of those halves, glued them together then shaved a bit more off the back since the lid is fairly shallow. Then lay out how you want everything, sketch outlines, and start carving. I used a melon baller and a butter knife for most of it. This stuff makes a HUGE mess, I had the vacuum hose handy and a small garbage can to drop chunks in.