An Engineer is someone who measures with a micrometer, marks off with a crayon and cuts with an axe. Lee Margetts (an I’m an Engineer, Get me out of here contestant) recently used this joke in one of his chat sessions. In my experience it’s “measures twice with a micrometer and cuts with a chainsaw”…
Engineers come in all sorts of flavours and for some a micrometer is a long distant memory. The underlying point of the joke though is that a lot of Engineers have an obsession with accuracy, an accuracy that can be achieved on paper but rarely survives first contact with reality. In civil engineering, for example, plans might be made to the nearest millimetre, but if you were to measure the building after construction then it is unlikely that it would meet the plans exactly. That is where tolerances come in – an agreement as to whether a pencil or a crayon is suitable for marking up, and whether or not it can be done by hand or needs a laser rule or some such. Modern manufacturing can achieve remarkably good tolerances repeatedly (for a price), but sometimes this is spurious and you end up paying for something you don’t really need.
When setting up any kind of project, it’s worth doing the sums to see if something is feasible. These sums don’t have to be ‘right’: it’s about being in the right ball park and seeing if there are any hot spots that are going to cause problems.
A back of the envelope calculation allows you to make a first-order approximation as to what’s needed or what the scale of the problem is. You would want to refine this before you bet the farm on anything, but as a starting point, a five minute investment in your time to run some simple numbers, check your thinking and decide whether it’s worth investing more time (time = money, after all) in your idea, you can’t beat it.