I just started an area of tapestry that will use a really fine copper thread as the weft. It's so fine it's like hair! Unfortunately it was breaking a lot --as it got caught on a nick in the wood of the shuttle, so it's going slower than normal what with tucking each old & new weft end in... I guess sanding that nick would be a good idea!
My hope in the end is to have enough woven for two mid-large pieces, each with this tapestried area to allow for playing with layers behind that transparent area. The reflective quality of the copper will also add an interesting element....