Paul, i was confused at first on this also. I am trying to remember but it has been a month or so and my memory is slipping. I believe you glue three 1/4 inch pieces together then add one 1/8 inch piece to each , then put one 1/8 inch piece in the middle. Look at the picture to the top very left above the wing on the plans, that is the way to build them. It ends up being one 1/8 piece on the top, then three 1/4 pieces , then one 1/8 piece in the middle, then three 1/4 pieces again and one 1/8 piece on the bottom. I hope this makes sense. Ray