I managed to find a GT Moto tool tube on eBay and have fitted that to the Hepco and Becker pannier rails with 16mm P clamps. In hindsight 15mm would have been a tighter fit. The tool tube is sturdy and a good diameter to get shorter tools in. However it was not long enough for tyre levers. I sorted this by getting an extendable art tube for just over £6. It fits a treat above the main tool tube with reusable cable ties. That should keep the weight nice and low down on my planned tour to the Picos and mean I can take everything I need to change a tube if needed.