The art of cobweb painting, or gossamer, involves gathering, cleaning, then layering the silky excretions of web-spinning insects such as spiders and caterpillars, to form a canvas. The vast number of webs needed to build a single canvas meant people were employed solely to collect them...
The fashion of cobweb painting seems to have begun in 16th-century Austria, specifically in the Tyrolean Alps where monasteries and convents would produce these micro meticulous masterpieces.
There are less than a hundred cobweb paintings in existence today. Here's the only one in England:
Madonna and Child, Chester Cathedral
probably by Johann Burgman (d.1825)
The above cobweb painting is a copy of this oil painting by Lucas Cranach the Elder (just wanted you to get a better view):