The phrase "as a cupboard" is correct and usable in written English.
It can be used in contexts where you are making a comparison or describing something in relation to a cupboard, often implying storage or containment.
Example: "She organized her thoughts as a cupboard organizes its contents, neatly arranging each idea in its place."
Alternatives: "like a cupboard" or "similar to a cupboard".
She describes her Leningrad prison cell rather cheerily as "a cupboard".
The bathroom had originally been crammed into a small space that now serves as a cupboard filled with cleaning items.
Think of your knowledge system as a cupboard with hangers and the new material as items that need to be hung up.
Or, in a more sinister vein, the desired truth "just kind of sails overhead / like a turkey vulture, on parenthetical wing, / empty as a cupboard".
She was rounded up by members of the secret police and tossed into a Leningrad prison, where she spent months alone in a cell she describes almost cheerily as "a cupboard".
Its boss, Devyani Raman, described India's luxury-goods market as "a cupboard full of beautiful clothes with a new outfit arriving every day it could start to look messy without the right care".
But coming on the heels of last year's insubstantial "Irrational Man" and the most unmagical "Magic in the Moonlight," "Café Society" is instead a happy reminder that even a cupboard as over-raided as Allen's can sometimes yield lovely, melancholy surprises.
Maria spends her short nights between exhausting shifts as a maid in a cupboard in her employers' home in Hong Kong.
Morley ends his moving paean by imagining Bowie, close to the end of his life, crouching in a cupboard as he films the video for his final single, Lazarus, in which – it became clear – he told us he was dying.
Lilo and Stitch 2002 The BBFC were concerned about children copying a scene in which Lilo hid in a washing machine, and Disney agreed to replace it with a cupboard as Lilo's hiding place.
I hated the idea of "vintage potatoes" – the v word is bad enough when applied to secondhand clothes, but with food it makes you think of an old tuber in a cupboard; as a food word, "vintage" is even worse than "heritage" or "heirloom".
