Staying with the topic of membrane threads - one of the steps is, of course, to apply leaf metal to the organic substrate. In the original finds, this was very often gilt silver leaf, making the layer of gold even thinner and thus the whole thing even cheaper.
There's several different methods for gilding, and we used a modified form of water gilding for most of our tests. And because that is a very interesting thing unto itself, here's a nice video from the V&A about how water gilding is done:
I came across this video looking for the English version of some gilding terms, as I only knew the German ones - and I learned that for the last step, the application of the gold leaf, different liquids are used. I learned to do it with a mix of alcohol and water (and the German term for that is "Netze"), but I've found instructions now mentioning fish glue and just pure water.
The methods to transfer the gold leaf to the cushion vary as well. It's really, really fascinating!