For reference, here's a diagram of two 12mm shafts, CF and solid maple, showing how thick the CF walls need to be in order for the shafts to have equal mass (assumes CF's density is 2.5 times maple's). Presumably, these would produce equal deflection. If the maple shaft was hollow at the tip, the CF walls would need to be thinner.
View attachment 884597
And here's the same pic reduced to show them at more or less normal size:
View attachment 884614
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