A sticky-backed version of dissovable film that will hold loose fibres in place while machining.
Remove cover sheet to expose the sticky surface and place scraps and/or individual fibres & threads in position as desired. Once the arrangements are completed place a piece of dissolvable film (either Heavyweight - more see-through, or Lightweight - more frosted look) over the top. This sandwiches the sticky surface and fibres and makes it safe to run through the machine.
Once work is complete, dissolve in cold water. Both Aquabond and the dissolvable film will disappear leaving only the scraps/fibres/threads and the machine stitching.