Ersatz is a feyborn goblin who resides in Finder's Keep. He serves as personal artificer to Bossman Gyp, although none of the other Finders pay him any respect for that station. Despite his ridiculous voice, Ersatz is perhaps the most reserved of the goblins (although some of his creations have been extremely loud indeed).
While most of his inventions have resulted in far more harm than good for their users, he has stumbled accidentally into more than a few successes. His Gust Glider, for example, is integral to life in Finder's Keep.
Less helpful, perhaps, was his "Tumblebomb." Although it was certainly an effective repurposing of the region's giant tumbleweeds, the explode-on-impact portion of the project resulted in the destruction of nearly every goblin guard-tower in the area.