So, I think I'm gonna self-publish an instruction manual
A few years ago, I was writing some stuff up for an invention I had developed, but thought I had lost it all to two completely separate hard drive crashes in the space of a few weeks. I just found a draft of the document and some of the CAD drawings in a badly damaged backup DVD. Most of the really critical information that I couldn't reasonably duplicate is there, and I can recreate the rest now.
It's in an odd hobby niche where there are many well-defined web forums dedicated to the general subject matter. The materials don't seem to run afoul of any of Amazon's content restrictions (it's not sex or porn related, which are the only things they seem to care about -- anyone know of any other subject areas they frown upon?). I think I can price it fairly high and still not drive away buyers, because the relative cost to build my gadget as opposed to commercial stuff saves about 80% of the cost. I think I can come up with a side business selling components.
Overall, it seems to fit the self-publishing model extremely well. Any other things I should think about?