Have you not come across Jon Goodman's kits? Here are instructions for the EL and FT and the size of foam you need:

http://www.kyphoto.com/classics/seal/Nikon_EL.pdf
http://www.kyphoto.com/classics/seal...kkormatFT3.pdf

Contact him at jon.goodman@yahoo.com for his kit, which is a real bargain -- comes with different thickness of foam, precut, and a tool.