Aw... a cute little set. This is a flat set of chipboard pieces (with score lines) to build a small accordion-fold booklet that fits inside a matchbox (box plus sliding cover). Plus the booklet has a mix of building roof silhouettes so you can play with how you decorate, and you can see a preview when the booklet is folded closed.
The matchbox itself is approx. 1-3/4" x 2-1/8" (x 3/8" deep) when closed. It's got a lot of wiggle room so you can paper the matchbox (and embellish the booklet) and still slide the matchbox open.
One set (3 pieces).
Teri Calia made "A Paradox" Skyline Matchbox Book (see the wide photo below). More info in the blog and/or see the supply list.