I have far too many projects under way Simon – so it's not just a problem with choosing just one from all those interests, it's also managing to stay focused on just a few and completing them. I tend to work on something for a while and then there is either an "interruption" or a "distraction".
Interruptions are where I have a problem with something, such as not being able to make it to my satisfaction, having the right tool or material available – or often just not being able to decide how to proceed next… So 'it' gets put to one side until the right part, tool or inspiration comes to me…some years might pass before I will return to it.
Distractions are where something really interesting pops up and I'm tempted to "just have a quick look at it" – several very pleasant hours, days or months may pass until (once again) I am "interrupted"….
And so it goes. Somewhere in my families past, we must have been involved with Butterflys – as it seems I have a Butterfly gene hiding within me somewhere.
To be aware of the problem does help keep one a little more focused but I have also managed to rationalise the problem too. After all, if I am generally happy (and enjoy) fliting here, there and everywhere – then perhaps that is the whole point of a hobby. Fortunately, I'm not making my living at it…
But another factor is beginning to help me stay a little more focused and that is the increasing knowledge that many of my more ambitious projects may never get finished in the time left to me – so some hard choices will have to be made I'm afraid…if only to tidy things up a bit
All a bit depressing I'm afraid – but then gain – there was that very interesting article about a low-cost CNC machine the other day that I must have another look at…. 
Regards,
IanT