Notes on specific Laws - the Zeroth Law Answered
This is where the whole Law thing started:
There is a fairly regular kind of thread that appears here.
It starts should I make an Instructable about insert topic here?
You know what? The answer is yes. Even if nobody else on the site is even vaguely interested in insert topic here, it is probable that somebody with access to the internet, somewhere in the world, will eventually develop an interest in insert topic here and resort to Google. Since this site is googlable (is that a word?), they can end up here, grateful to you and potentially a new and useful member of the site.
So, unless it breaks the guidelines for what is suitable here (basically, Please remember that this is a family site), and you're not just re-inventing the wheel, then the answer to should I? is always yes.
This has become the Zeroth Law:
If an Instructable exactly like yours has not already been posted, then you shall post your Instructable.
Instructables are, after all, the whole point of this site. If nobody posted new Instructables, the site would shrivel and die.
It doesn't matter what you make, as long as it falls within the bounds of "good taste" (define them how you will). What does matter is that you make. If you look at other sites limited to making only one kind of thing (jet engines, chests of drawers, whatever), they tend to have a slow input of new projects, with many variations on a few basic themes posted early in the site's history. Instructables has a daily project count that rarely drops below ten, and sometimes hits thirty.
Addendum to the Zeroth Law
If your Instructable has an identical goal to a pre-existing Instructable, but achieves that goal by a different or improved route, or in a different style, then you shall also post your Instructable.
Why the addendum? Sometimes potential posters worry - there's already a project quite like mine, so should I waste bandwidth with mine? Of course you should! Some people will prefer the first version, but other people will prefer your version - maybe it's easier to read, the photos are better, or they prefer your sense of humour. Maybe you use different raw materials, or use different tools. Either way, unless your Instructable is indistinguishable from an earlier project, you should post your own.