Abstract: A tool packaging container including a rectangular body portion having a recess at a central portion, a flange at a bottom, and a plurality of vertical dovetail grooves at both sides, and two rectangular extension containers connected with both sides of the rectangular body portion. Each of the rectangular extension containers is one-half as long as the rectangular body portion and provided at one side with a plurality of dovetails and at another side with a plurality of dovetail retainers. The dovetails of the rectangular extension containers are adapted to engage the dovetail grooves of the rectangular body portion and are adapted to engage the dovetail retainers of another one of the rectangular extension containers. Each of the rectangular extension containers is formed with a neck at an upper portion, a pair of lugs at one end.