The Ub3r-Spanner

In order to craft this gadget you'll need to kill 2 Dungeon bosses on any difficulty other than m+.
[item=168153] drops from the 1st boss of MOTHERLODE
[item=168154] drops from the 3rd boss of Temple of Sethraliss

The next item in the recipe can be obtained by looting two world rares. (Remember that you'll need TWO of those thingies! *sigh*)
[item=168152] drops from [npc=139328] and [npc=139205].
(To activate the Sabertron, you need to kill the Sabertron Technician next to the red cat)

The other ingredients are nothing special.
Storm Silver Ore and Platinum Ore can be mined or bought at the auction house.
Insulated Wiring comes from scrapping or pickaxing mechanical units and is also sold by NPCs pretty much everywhere.
[item=152668] is obtained by scrapping, transmutation, or as a reward from worldquests. (Btw: Scrapping a (non-crafted) trinket will always give you an Expulsom)

EDITED to include Sichels additional information. Thanks!

I would just like to say that this item is unusable in Islands, Dungeons and Raid. Don't even bother acquiring it.

I managed to solo the requirements and get it on the PTR. It has a 15 min cooldown and summons 1 of 3 random constructs(Boombots, an advanced target dummy and a mechanical hound construct). Although they are summoned at random, you also get the recipe to create modules which are consumable items that guarantee which type of construct gets summoned for the next 2 hours. The target dummy was a large jukebox with a cardboard in front of it taunting nearby enemies and has 130k health, while the boombots are pet bomblings that charge and explode(they all missed). I never tried the hound one.