|Spare rails. Perhaps the crew is looking for a length of rail for urgent repairs of the line?
The roof is dressed in my favourite tarpaper material, micro pore tape. It's a tape from the health industry made to position and fix bandages and still allow the skin to breathe. When painted it retains a slightly rough surface which resembles tarpaper. The tape is self adhesive, so it's easy to attach. The tape doesn't seem to loose its grip over time. I have had tape on a roof now for more than five years without any 'slipping'.
The previous post on the speeder covered the electrical parts. Earlier posts can be found here:
Drawing and the first plastic cut
Parts cut out and ready for assembly
For those who care, even more images of the speeder's construction can be found in the Flickr work bench-folder.