The Sparklematic 5200!
Put a Grime-Encrusted Object and 3 silver into the Sparklematic 5200 to get a random item back.
Put a Grime-Encrusted Object and 3 silver into the Sparklematic 5200 to get a random item back.

Repeatable: bring every Grime-Encrusted Object you loot.
The client also has variants of this quest (ids 4601, 4602) that work the same way.
Not yet confirmed by players in WoW Forever; details may differ.
Both factions: The Sparklematic 5200 in Gnomeregan.
Both factions: The Sparklematic 5200 in Gnomeregan.
Sparklematic-Wrapped Box.
The Sparklematic 5200! is a level 30 quest; you can pick it up from level 25. It takes you into Gnomeregan.
Sources: Quest data from ForeverDB.net · ForeverDB: Gnomeregan · ForeverDB: Grime-Encrusted Ring · ForeverDB: The Sparklematic 5200! · Warcraft Wiki: Gnomeregan (instance)