I used the Silhouette Cameo to cut my paper parts, but a good blade wielded by hand could easily do the same.
From the little triangles and squares, I used tacky glue to build likely shapes- they can be stuck right at the edges, even, for a pleasing geometric look.
I then formed my shapes into an imitation of the Mountain shelf, which can be seen in the gallery of the J1 Studio.
Prototyping in paper really helped me get a feel for how the structural components fit together, and how many of each component I needed. And now I have a miniature shelf!