Although this may remind you of a G.E.C.K., it is really just a standard metal briefcase.
Standard metal cases can be obtained primarily via a few of the in-game quests, including these:
Metal cases are the primary target items of these quests and are thus intended to be returned to the NPC who gave the quest to you. However, sometimes a metal case will contain items that are considered to be more valuable to the player than completion of the quest itself. So sometimes players will choose to let the quest fail, open the case instead, and get the contents.
In some cases the contents are blueprints, which can either be used by a professional crafter, sold or traded.
Be careful! Metal cases might be rigged with explosive Traps!