I use burr tools a lot - but have started designing puzzles with the aim that they cannot be solved using burr tools. My exchange puzzle for IPP this year is one such puzzle (Eric is making it and will have some to sell after IPP).
I find playing with as many puzzles as possible helps the design process. In trying to solve a puzzle I usually come up with a couple of different ways that I would have made it. Another good idea is to watch people solving puzzles. See what they try, how they hold the puzzle etc. This lead me to design the Sly Burr, and if you have it you will hopefully see what I mean from the first move.
Thirdly is what I call 'divine inspiration' an idea will come to you whilst looking at everyday object (yes I am obsessed!!), and how you can use the object in a puzzle.
Burr tools can be found here;http://burrtools.sourceforge.net/
I like the idea of a kinetic sculpture - you should pursue that one