RE the need to get permission from the designer to teach a published model in an informal (you are not being paid, no one is paying to to be taught by you) forum whether to one person or many; I think this is the forum in which most origami teaching is done.
My rule has long been to teach anything I like in such a forum without seeking permission. I always give (sometimes in writing) the name of the designer if I know it, the title and author of the book if it came from a book, the name or URL of the website if it came from a known legitimate site and who is the site-owner if known. I can't think, at the moment anyway, of any instance where I taught a model to anyone without knowing where it came from and telling them that information, even it was just "so-and-so taught this to me at the Sept club meeting, I don't know whose model it is" or "I found this on a table at the last club meeting and reverse-engineered it, I don't know whose model it is". In other words I think it is *very* important to give credit to designers and publishers, always, and strive to do so, always. Maybe they don't get paid for the sharing, but their name is mentioned, or at least the idea of there being "a designer", and advertising is accomplished. I do consider that if a model diagram has been published legitimately with the designer identified, that the designer is OK with people learning, folding, and even sharing the model with others, as long as it isn't done to steal from the designer in some way. If you really don't want anyone to fold your model without you getting paid in some way, why allow it to be published in a book or on a publicly-available website? It could end up in a public library, or for sale at a garage sale for 50 cents. (I know this view isn't technically correct, but it's reality, follow the Golden Rule and we'll all be better off.) I also consider that it is good advertising to teach a model from a book or website, and give the information so the folders could look up the information if they wish, or buy the book. I don't think it would be right to teach every model in a book, nor do I make copies of diagrams from a book or website without asking permission, in general. I confess to occasionally making a copy from a book, when asked by a friend, and I have been known to make my own diagram or Step Photo diagram for a model for which I only know of a video or I only know of it from being taught by someone in person. This is for my own use, but I have on a few occasions shared such constructions with a friend, always making sure to write on the diagram who I learned it from, when, and the fact that I don't know the designer and don't own the copyright. I would not make a bunch of copies for a class or club meeting (unless I had permission to do so). I always tell them to look it up, or they can make their own Step Photos while we fold (very few people do this BTW). Finally, there are so many nice Traditional models out there, and since they tend to be on the easier end of the spectrum, they are ideal for most public teaching, which is usually done for the benefit of non-folders. Why not use them for such forums? I find that people are usually delighted to be re-acquainted with a model learned in childhood, or to finally learn a model they've long heard of or seen pictures of. Kids who know the model often want to teach it themselves and unless there are time contraints, I'm happy to let them do that. This is also a good time to make a comment on the idea of Traditional models vs models designed by known designers, and models published and copyrighted.
