OK, Positives first:
I love this. A unique Goblin building, very simple but almost universally-useful in it's simplicity. A tower, a farm, a factory, a depot, an engineering bay... It could be anything! And while it's easy to see what each part comes from, it's an eclectic & unique mixture that I have yet to see (Rizz_Boomer's notwithstanding); a fitting homage to RB's building (which is also stellar).
The only things I could see changing:
- It almost seems
too perfect... As in, too symmetrical, too even. Goblins are renowned for haphazard, confusing machinery & architecture; crooked stuff, bent things, strange pipes. This is almost too 'clean'. Perhaps it could be tilted a bit (aka "leaning tower of gob-isa"

)? Perhaps one of the gears could rotate in the
opposite direction (and/or @ a different speed)? Perhaps a few extra doodads to emphasize the cluttered, unkempt nature of Goblins (boxes, explosives, extra pipes, flags, etc).
- Along with the last bit of the above comment, I would consider some more TC. If you're not sure where it could go (neither am I), perhaps a nurny-addition could provide the space (see above).
- I really can't think of what exactly this is to be used for; in part it's "anyman's building"-ness means it's not particular enough.
What did you you have in mind for it? Ah, seen your above comment. Welp, that makes sense. Though of course, depending on what kind of casters you have in your Goblin race, this might need some specialization (i.e. Alchemy-dudes, or Mech-dudes, or Explosive-dudes) as in the above. Meh, maybe.
Very good work. I'm excited to see more Goblin/Building/whatever models from you (and for the former, let me know if you need any...
inspiration 
)
//EDIT// - So you too are making a Goblin race? Lol, who isn't. : ) I would love to hear more about that...