Buttercup Toy (Fallout 3)

The Buttercup toy is a smaller variant of the pre-War robotic horse Giddyup Buttercup, found on Mothership Zeta. It can be used as ammunition for the Rock-It Launcher. In Fallout 4, it is a reward item in the unmarked quest Giddyup 'n Go.

Mothership Zeta

 * One of the Buttercup toys can be found inside the research lab. Find the room with full-size Buttercups on giant shelves. From the overlook, looking over the shelves/rows of life-size Buttercups, one can easily see a small toy-size Buttercup on a shelf. While down there next to the shelf, simply jump and grab it, or shoot it off from the overlook and go retrieve it.
 * A second can be found after the Lone Wanderer has both visited a few of the other locations connected to the engineering core, and destroyed all three generators. It appears on the bottom floor of the engineering core, on a table near the makeshift bed where Toshiro Kago usually sits.
 * A third Buttercup toy is also in the engineering core, on the table next to the pre-War bed near the broken teleporter that will later lead to the observation deck. The table is always there, but the toy only gets placed on it after visiting the engine room and the three generators are destroyed.
 * A fourth can be found on the shelf above the unique atomic pulverizer behind a lock (75 Science skill) in the weapons lab, that can be alternatively reached through the console beside the door.

Fallout 4
Given by Arlen Glass as a reward for fetching him the parts needed to restore a Giddyup Buttercup in Giddyup 'n Go. To get it as a reward, aside from doing the quest itself the Sole Survivor must obtain Marlene's holotape from Arlen's office at Wilson Atomatoys Corporate HQ, a new dialogue option will be unlocked that allows the Sole Survivor to give him the tape and caps will be given as a reward, as well as a unique version of the Giddyup Buttercup toy called Buttercup toy, that goes under Misc section and only has a weight of 2 instead of 8 and cannot be scrapped. Without the holotape, Arlen will only give caps as a reward for completing the quest.
 * One should note that this model of Buttercup toy does not look like the one from Fallout 3, instead it's identical to the model from Fallout 4 in every way, except in size as it's far smaller.

Gallery
Buttercup-Spielzeug Игрушечный конёк Іграшковий коник