An optimization model for plastic frames of minimal construction time is developed. The problem is reduced to a minimax problem for a set of inequalities. The linearization leads to a linear programming problem of a slightly larger than usual dimension, but this problem could be solved using standard software. The procedure is illustrated by examples of some frame structres. The results show that the approach is more optimization-efficient than the traditional design for minimum weight and each of the two formulations leads to a different design.