I have recently been involved with work where I have been required to create guitar parts for performances of songs where the original pieces of music ( or versions which I have been sent ) contain no guitar parts. This leaves me having to create parts for myself. This is not an unpleasant task and can, in fact, provide an opportunity to get creative and 'do your own thing'.
Here is a recent example. A performance with Mica Paris on The Javone Prince Show ( shown this month on BBC2).