A pochade box is a small wooden box, about the size of a large coffee-table book or a very small briefcase, that is placed flat in front of you or upon your lap and then opened up so that the lid (locked in roughly vertical position) becomes your easel, with all your painting supplies contained in the large part of the box. It of course accommodates artwork no larger in dimension than the lid, but the intention of it is to permit plein air (or front seat of the car, or boathouse, in inclement weather) paint sketches. A mini French or field easel without the legs. Crawshaw uses them all the time. (He has a number of videos out, you may know, all collections of half-hour BBC episodes, so nothing very "finished", but the guy is such a delight and inspiration (his trademark sign-off: "It's easier than you think! Why not have a go?") that I feel almost remiss at never having sought him out personally when I was visiting in the U.K.)
By the way, a book you might find instructive at this juncture (and which you might have to have Amazon.com send over to you) is
Becoming A Successful Artist , by Lewis Lehrman, a collection of 21 "interviews" with successful artists who tell their tales, often of difficulty, circuity, and serendipity, relative to both becoming adept at artwork and learning the marketing business. [Later note: I've just discovered that the book is out of print, and may only be available through a used-book dealer, online or elsewhere -- sorry.]
Cheers,
Steven