ABSTRACT
The box contained two types of steel balls for each case; pinballs and unfinished pinballs as shown in Fig. 2. These equal-sized pinballs have about 11 mm diameter but it is dispersed as shown in Fig. 3. These pinballs are stacked up in a simple stagger pattern only in one vertical face shown in Fig. 4, but not in the other vertical plane to imitate two-dimensional condition.
