I should clarify that I drew the chassis in Sketchup using the tubes in the book which produced a very different shaped result to that on page 34. BR3+4 are not at a true 10 deg which puts BR1+2 out of place as a result, I've had flat pack builders tell me that their chassis are +/- 5mm out in overall length.
I've changed the drawings to read as outside corner to corner measurements which should be easier to do using a tape as intended rather than trying to read internals with a floating tape measure.
Sorry for any confusion caused.
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