The question doesn't specify the size or shape of the counters. Let's use circular counters. 9 of them have the same radius. The remaing 3 have three times the radius of the smaller counters. Put the 3 large counters in a row so that the middle one touches the other two in a line. Take 3 smaller counters and place them on top of one of the large counters to form a flat column (not a stack), the middle small counter touching the other two in the column. Similarly place the remaining 6 small counters on the two remaining large counters. Each row and column now has 4 counters. The small counters form a square in 3 rows and 3 columns.