I've seen many people make this album - including Paige Taylor Evans. I didn't have a Silhouette Cameo machine though so I hunted around to find measurements to cut my own! I used kraft paper and paper from the Echo Park "Passport" collection.
My album measures (closed) 3 1/4" wide by 9 1/4" high and (open) 12" wide by 9 1/4" high. Each square measures 3"x3". It opens up accordion style. Both sides of album can hold photos, pockets, embellishments and more!
There are many tutorial online if you Google "Trifold Mini Album". All the tutorials vary in their measurements, but it can be helpful to see a video.
These albums are fun to make and are perfect gifts!