Well ,some of the challenges to mixing at home depend on getting the chemistry. The Formulary stocks HAS, but cannot mail it outside of the US.

I have a good stock of CD-4, which they can mail me. It is nothing to dream about fabricating at home.

Read up on the history of a dye maker, that a few years ago, shut down in Buffalo NY. I saw the ongoing demolition and clean up efforts as a part of a trip there last weekend.

It went by a series of names in the almost 100 years it operated. The longest lived name I think was National Analine. Its final name was Buffalo Color.
The steps to fabricate some of the dyes, as well as the feedstock volatility and flamability issues are mind boggling. To think that a lot of this was worked out by the 1920's has amazed me.

With color photography what we essentially are doing is splitting the dye so that the second half is the oxidation component of the color developing agent.