  Various upper and lower bounds are provided for the (angular) Kronecker constants of sets of integers. Some examples are provided where the bounds are attained. It is proved that 5=16 bounds the angular Kronecker constants of 3-element sets of positive integers. However, numerous examples suggest that the minimum upper bound is 1=4 for 3-element sets of positive integers. 
Upper and Lower Bounds for Kronecker Constants of Three-Element Sets of   Integers