The main wing spars are being built in the workshop right now. This is a long process because of the hundreds of layers of carbon required. The “uni” or unidirectional carbon fibres are prepared in stacks of 5 layers before being interleaved with conventional carbon cloth that has fibres running in two directions. Then we alternate those directions to zero and forty-five degree alternates.
This photo shows the inside of the spar near the wing tip. The joins in the 0 and 45 cloth layers show up as raised lines in the bottom of the trench. These joins are up to 25 layers below the surface yet they are still clearly visible. The process of compressing the layers until they are completely melded is extremely efficient. Seeing it this way, you can appreciate the effort that has gone into extracting the maximum strength from the minimum weight.