Tangentially related here (pardon the pun), after trying dozens of trials and freeware a couple of years ago I ended up installing two programs on my computer that enabled an unschooled nabob to draw simple circuit diagrams, labels, and 3d drawings. DIA is a tiny little freeware diagramming program that is smilingly intuitive (and obviously limited for any professional purpose, but that's fine with my needs).
Google Sketchup free version is also remarkably intuitive. I've been able to email 3d viewable versions of ideas/objects to others by using Sketchup. This isn't photo editing, but kind of on topic here anyway.