The contour method which was originally designed for $2{ imes}2{ imes}2$ contingency table is studied for $2{ imes}2{ imes}K$ and $2{ imes}3{ imes}K$ tables. Whereas a contour plot for a $2{ imes}2{ imes}K$ table is represented on unit squared two dimensional plane, a contour plot of a $2{ imes}3{ imes}K$ table can be expressed with a regular hexahedron on three dimensional space. Based on contour plots for categorical data fitted to all possible three dimensional log-linear models, one might identify whether $2{ imes}2{ imes}k$ or $2{ imes}3{ imes}K$ tables are collapsible over the third variable.