The trim was just a chain the length of the circumference of the shade, plus a little bit, then working backwards and forwards in double crochet until we thought it was deep enough. The work was joined into a circle and pulled over the shade. I had thought it would need some PVA glue but it has stayed in place.
Quite pleased that I have designed this, used materials I had, these bought back memories of the evening classes again. The Internet, knitting shows and groups have replaced evening classes for yarn work, but there must be other subjects where an old fashioned class would be helpful in acquiring or learning skills. Ian wanted to learn wood sculpture, he is experienced in carpentry and making models in wood, he enrolled for a Saturday class in the subject, then the class was postponed, then cancelled as the adult college couldn't find anyone to teach the subject.