It will automatically choose the largest obstacle it can place based on how much you drag the mouse - I believe the largest we have is 5x5 for the rocks. With the exception of the desk, all obstacles have at least two sizes.
Incidentally, obstacles have different colours depending on what theme they appear in, and all obstacles appear in all themes. So don't be shy with those obstacles, guys, as they'll look great even if you're working in Iceworks.
Bonus points for anyone who uses the large statue in conjunction with a secret passage, either pointing towards it or using it as misdirection.
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What do you call an elephant at the North Pole?
Click here to view the secret text
×Lost.