Open Source Hormone Production
This page has the purpose of collecting several approaches to create the hormones necessary, as well as provide information about art projects that try to do so.
Synthesis and extraction approaches
Ways to synthesise or extract estrogen:
Synthesis from Cholesterol
Extraction from Horse Urine
Historically the first approach to extract estrogen was the extraction of estrogen from pregnant horse urine. The process is straightforward and is well described in literature: http://www.jbc.org/content/126/2/663.full.pdf
The conjugated estrogen is also sold under the brand name Premarin (a contraction of "pregnant mares' urine"). Premarin has more side effects compared with other forms of estrogen.
Another way to produce estrogen is using tissue cultures:
Current Art Projects concerning Open Source HRT
This is a collection of art projects regarding Open Source estrogen.
Mary Maggie wrote her master thesis about an open source estrogen art project and produced videos on the topic Her website: 
Her master thesis: https://www.media.mit.edu/publications/open-source-estrogen/
Rian Hammond is working on Estrogen producing fungi.