They are not new. Far from it.
People have been making cardboard model buildings since the 17th century. Now the models encompass everything from aircraft to sneakers or motorcycles.
For $9.99 I bought a postcard sized package that had fifteen 3x5 sheets of cardboard with Buckingham Castle (including Big Ben + Parliament) printed on one side in color/colour.
An Exacto knife, a ruler and some Elmer's and a piece of wood with which to mount the model.
That is all that is needed in most cases.
If you are really meticulous you will also need toothpicks for cleaning joints and also to act as gussets in strategic corners.
And then it is nothing more than cutting and folding and gluing. The folding being the most exacting part of the process. Sharp corners are not always easy to achieve with cardboard, thus the need for the straight edge.
Modeling is an exercise in patience for the most part. You are alone with your thoughts. They do tend to be about the model under construction.
I like to play some mood music or have a theme movie playing.
I always found modeling to be very therapeutic.
These types of models are very popular in Europe. Poland, the Czech Republic and the United Kingdom seem to produce the most in terms of numbers as well as complexity.
Found on eBay for $15 with shipping.
Do not expect a perfect package. Many times the pages have been printed in a haphazard way leading you to think half of the instructions are missing et cetera.
Give yourself a good few minutes to 'catalog' exactly what you have in your hands.
(Ah, the first half of the illustrations are in the back of the book while the second half are at the front)
What led me to looking for these models again, I am not sure. Maybe I need some therapy.