I haven't done a great deal of canvas work, partly because I'm not sure the technique, in general, gives the effects that I prefer.
However, I did come across a particular book I found very inspiring, because the authors incorporate a lot of metallic threads in their designs.
Link to book details here
This small practice piece of mine, above, will probably go in the centre of a small cushion (one day!).
Here are a couple of photos from the actual book: