Rummage Through Scrap

Ok. So you are an Engineer and you want the 4 toys that come from ‘Rummaging Through Scrap’.
Dented Can
Malfunctioning Stealthman 54
Defective Doomsday Device
S.E.A.T.
Let me explain this confusing mess to the more junior members of our Wowhead family. Fastest and most reliable way to get ‘Scraps’ is to target an LFR Boss with a quick reset. Introducing LFR ‘The Waking Dream’
1. You must have the ‘Ashjra’kamas Shroud of Resolve’ Legendary Cloak in your bag
2. Here’s hoping you played through the ‘Battle for Azeroth’ expansion and acquired the Cloak
3. As an Engineer, make the highest quality ‘Tinker: Plane Displacer’. Or simply purchase the 3 star one on the AH (700 gold on my Realm)
4. Have a set of Engineering goggles for your class (make or buy one) and ensure it has an available ‘Tinker’ spot (presumably other items that have an available Tinker spot will work)
5. Slot in the ‘Tinker: Plane Displacer’ into the vacant ‘Tinker’ spot and equip the item
6. I put the Goggles that held the ‘Tinker: Plane Displacer’ on my bar for one click access
7. Head to Boralus in Tiragarde Sound (Alliance) or Dazar’alor in Zuldazar (Horde)
8. You will need to engage with Kiku inside the Snug Harbor Inn. 74 13 who is on the right as you enter the Inn. Or for Horde please see Eppu located inside the Hall of Chroniclers, on the 2nd level of the Great Seal in Dazar’alor (the room right by the Guild master & vendor) – 70 32
9. These 2 people will allow you to list for all LFR in the ‘Battle for Azeroth’ expansion. With the Legendary ‘Shroud of Resolve’ in your bag the LFR ‘The Waking Dream’ is now available for you to list for (no need to equip the Shroud)
10. You are only interested in the first boss ‘Carapace of N’Zoth’ also known as ‘Fury of N’Zoth’
11. Upon entering that raid Wrathion will be there. Just click on him to say ‘I’m ready’
12. Clear the trash in front of ‘Fury of N’Zoth’ so he can be engaged
13. Click the goggles on your bar and go invisible. As soon as you do this a ‘Piece of Scrap’ will appear in your bag (sometimes 2)
14. Sweet. This is what it’s all about
15. Now run up ‘Fury of N’Zoth’ (if still invisible right click on the ‘Plane Displacer’ buff icon top right to remove the buff so the fight is engaged (no DPS). You will be Mind Controlled within seconds and the boss disappears (resets)
16. When he disappears the 10-minute timer on your ‘Tinker: Plane Displacer’ will also reset (yay)
17. Click the Tinker again. You receive another scrap and the 14 to 16 second timer on your invisibility will count down to zero before he reappears. MC again. Reset again. You don’t’ even have to move
18. When you get 25 ‘Pieces of Scrap’ Open your Engineering panel and ‘Rummage Through your Scrap’
19. Please steel yourself for disappointment. As everyone has stated the drop rate is horrendous. Even by Blizzards standards
20. After your disappointment go back to Step 13 and go again
21. After you have done this a few times you will work out a few tweaks to improve your time management
22. After you have done this a million times you might have the 4 toys from Rummaging through Scraps
23. Alert. Occasionally the Plane Displacer Tinker will ‘malfunction’. No stress. Just engage the boss to reset the Tinker. You could throw more ‘Knowledge’ points at Specializations > Mechanical Mind > Inventions to reduce Tinkers from failing. But that’s quite a commitment to go down that pathway (after a few fails you may think differently!)
24. addon. Not just a horrible drop rate but RNG which toy drops. The same toy may drop multiple times before you get that final one. To cheer you up these toys can go for good gold on the AH
All the very best with your toy hunting

EDIT: As of 10.1.5, it appears that the drop rate of the toys has been increased to 10%.

Here's my results for 700 casts of Rummage Through Scrap (from 10.0.5):

426 sets of vendor trash (60.86%)
[item=41338] x103
[item=36812] x86
[item=169139] x82
[item=169132] x79
[item=169146] x41
[item=41337] x37
[item=169138] x33
[item=42931] x29
[item=36811] x22
[item=169143] x21
[item=169145] x19
[item=42930] x18
[item=36813] x17
[item=36814] x15
[item=169135] x12
[item=169130] x9
[item=200248] x2
(totalling 196g 66s 59c)

209 Dragonflight parts (and materials) (29.86%)
Handful of Serevite Bolts(T1) x26
[item=198184](T2) x11
[item=198185](T3) x2
[item=198186](T1) x23
[item=198187](T2) x13
[item=198188](T3) x4
[item=198192](T1) x16
[item=198193](T2) x4
[item=198194](T3) x1
Everburning Blasting Powder(T1) x25
[item=198190](T2) x8
[item=198191](T3) x1
[item=198201](T1) x11
[item=198202](T2) x9
[item=198203](T3) x3
[item=198198](T1) x16
[item=198199](T2) x8
Reinforced Machine Chassis(T3) x2
Arclight Capacitor(T1) x9
[item=198196](T2) x11
Arclight Capacitor(T3) x5
[item=190395](T1) x1

34 Bombs (4.86%)
[item=198278](T1) x2
[item=198279](T2) x4
[item=198280](T3) x1
[item=198239](T1) x7
[item=198240](T2) x1
[item=198228](T1) x8
[item=198229](T2) x1
[item=198292](T1) x1
[item=198293](T2) x1
[item=198211](T2) x1
[item=198208](T2) x1
[item=198209](T3) x1
[item=198213](T1) x1
[item=199194](T2) x2
[item=199195](T3) x2

20 sets of old parts (2.86%)
[item=144330] x10
Gyrochronatom x8
Thorium Widget x7
Fused Wiring x3
Handful of Cobalt Bolts x1
Iron Strut x1

11 Toys (1.57%)
S.E.A.T. x6
Malfunctioning Stealthman 54 x4
Defective Doomsday Device x1

I was curious about this specialization so I put 40 points into it very early on. After 3 days of very frequently using my invis tinker and some dozen explosives, I somehow manged to collect 5 pieces of scrap. Rummaging through this got me 2 pieces of [item=169146] worth a whopping 64 Silver. Some dev has been trolling hard with this. This was the most underwhelming 3-day-grind of my life.