I don't know of a factory maker for an N-frame 3". I have one that I use for "field use" just like ClarkEMyers said. I've looked around and never found a currently made production holster for the gun - just too few made I guess. S&W did some back in the 80s, but they have been out of production for decades now.
Like Clark, I also don't like things on my waist when riding, or in brush or when doing chores/tasks/etc. I use a tanker style shoulder holster for that, which was made by El Paso Saddlery. They and many other makers can create a custom holster for you, shoulder or belt. Simply Rugged is another good maker.