Having bought a small sheet of aluminium from Car Buider Solutions, I found that my tin snips were not up to the job of making decent cuts - I think I got them from an autojumble. So, back to CBS. I decided on the aviation tin snips as they looked more controllanble than the standard ones and not much more expensive. They arrived promptly and well packaged. This morning, I put them to work - much better. Thanks guys!