= Spinning-book demonstration
Clemson's documented apparatus is a book held tightly closed with several rubber bands. Toss it freely with spin about each <principal axis> in turn: the stated visual readout is steady orientation for the smallest and largest <principal moments of inertia>, but a flip before the catch for the intermediate one. The same book and the two extreme-axis throws provide comparison controls; the bands support the <rigid body> approximation by restraining the pages. This is a documented qualitative demonstration, not a measurement of $\lambda_2$.<Spinning Book by Clemson University>[Spinning Book by Clemson University, physics lecture demonstrations, 1Q60.40: Purpose, Description and Equipment]{ref}
For a rectangular book with length $a$, width $b$ and thickness $c$, where $a>b>c$, a uniform <mass> model gives <principal moments of inertia> $M(b^2+c^2)/12$, $M(a^2+c^2)/12$ and $M(a^2+b^2)/12$. The intermediate <principal axis> runs across the width through the <centre of mass>; the maximum is normal to the cover. A marked cover or end helps distinguish ordinary spin from reversal of a directed body axis.
Interpret only the interval after release and before the catch: hand contact applies <torque>, whereas <gravity> in a <uniform gravitational field> has zero net <torque> about the <centre of mass> because $\int\mathbf r\,dm=0$. Air resistance, page motion, an imperfect release and short flight limit the approximation. A toss ending before the <perturbation> grows need not reveal instability. Comparable initial <angular speeds> and flight durations would improve the comparison; these are suggested controls, not quantified controls reported by Clemson.
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