Sometimes sourcing suitable maps takes almost as long as making the shade itself. The huge circumference of 50cm diameter drum shades requires the joining of three maps from the OS one-inch maps series (the ones I usually use) or two maps from the Pathfinder 4cm to 1km series.
The latter have paper covers which makes them rather flimsy and as I've discovered many old book shops don't bother to stock them. When you do eventually find the ones you're looking for the condition is not always good enough. With this shade, having at last found the two consecutive maps I needed, I discovered one had been buckled when used in the rain by its previous owner. I struggled to smooth it, before being forced to begin the search for a replacement.
My customer has been very patient, I am pleased with the result, but have to admit this is one commission I will be happy to wave goodbye to.