I sometimes enjoy using a view frame when I´m drawing, I find it easier to discover a nice composition with these little thingies. Usually I just cut out a tiny frame in black or white paper and carry along when I go out to draw, or I do as many others, and keep an empty slide in my pocket.
The problem with a slide or a piece of cut paper is that they are one format only. If I want the view frame to fit the size of my sketchbook I have to cut myself a new view frame every time I use a different sketchbook. And besides, I don´t always use the whole pages in my books, I usually make several drawings on the same page, so I´d need several frames, which of course is too much trouble to carry along all the time. I wanted a frame that can change it´s format to my liking.
I know there are ready made view frames to buy, among others Dick Blick in USA has something they call View catcher where you can change the format of the frame, but why pay for something when you can make your own for free?
This view frame is held together simply by the poster strips, so it´s easy to take it apart (whatever I should need to do that for), and it´s easy to change the format by simply sliding the slides (ha!) to the position I want. It goes all the way from a small square to the whole landscape spread of a Moleskine watercolor sketchbook (you can spread the slides even further apart than shown in the photo). Works like a dream, and it´s got it´s own place in my pen case now.