15/10/2021
Modelling a disc of mass $M$, as a cylinder of radius $R$, thickness $h$ and uniform density $\rho$, it's moment of inertia tensor about its centre of mass, $\bold{I}_c$ can be evaluated:
$$ \bold{I}c = \begin{pmatrix}I{xx} & I_{xy} & I_{xz} \\ I_{yx} & I_{yy} & I_{yz} \\ I_{zx} & I_{zy} & I_{zz} \\ \end{pmatrix} = \begin{pmatrix}\frac{1}{2}MR^2 & 0 & 0 \\ 0 & \frac{1}{12}Mh^2+\frac{1}{4}MR^2 & 0 \\ 0 & 0 & \frac{1}{12}Mh^2+\frac{1}{4}MR^2 \\ \end{pmatrix} $$
taking the x-axis as the cylinders's axis of symmetry with [1]:
$$ I_{ij} = \iiint_V \rho (r^2\delta_{ij}-ij) \mathrm{d} V $$