On an ordinary day, you might miss this slip of a shop wedged between a veterinary clinic and a grocery store in Paris' popular Bastille.
a young and slender person, a slip of a girl
The word seems to be used for people. Can it be used for objects? Is there a rule that prevents it to be used on an inanimate object? Can we use it in poetry, why and when?
I wouldn't say this is personification because we are not giving a human attribute to something nonhuman.
Let's look at this entry for slip:
slip noun (2)
Definition of slip (Entry 3 of 5)
1a : a small shoot or twig cut for planting or grafting : scion
b : descendant, offspring
2 a : a long narrow strip of material
b : a small piece of paper
3 : a young and slender person
// a slip of a girl(M-W)
We can use slip to describe something thin or slender as in 2a. That is how it's used in slip of a girl and slip of a shop. Both are described as being a slip (narrow thing/person). This usage of of is common.
of
preposition
5 (used to indicate apposition or identity):
Is that idiot of a salesman calling again?(Dictionary.com)
This becomes clear when we look at the image in the article. It's a narrow shop sandwiched between two larger ones.
Broadly speaking, you could use this of metaphorically:
