Diaper cakes - if you know about 'em come in

I know some people hate these - this post is not for you.   But seriously, it's not to be a debate about the merits.

For those that like them and/or know about diaper cake etiquette, please weigh in.

A friend's sister is throwing her a shower.  For her 3rd baby.  So we are already past the etiquette stage.  We have recently rekindled a friendship since college and I wasn't at the first 2 showers so I'm happy about this one and excited to go.  It is her second daughter and she has already posted on FB about consignment shops for selling clothes, so I don't think she has a huge need in this area.  She has registered for mostly essentials like diapers, diapers, more diapers, and then some small things like BPA free bottles and such.

Rather than giving a box of diapers, I thought I'd like to make a pretty diaper cake using the kind of diapers she wants (Pampers). 

Is bringing a diaper cake as a gift a no-no?  Is that the sort of thing that only the shower hostess would give?  Accents like onesies, burp cloths, bibs, and paci's or wash cloths, butt paste, baby wash, etc. were going to be part of the "decoration" on the cake.

Of course I'll also check with the hostess in case she has one already so it doesn't compete with hers.  But I wondered if this would be a weird gift?  I think a box of diapers is boring...