According to a 1953 study on nipple and areola growth conducted on castrated guinea pigs, crystalline estrone caused high levels of growth that matched estrogen.
https://pubmed.ncbi.nlm.nih.gov/13052989/
I had tried Life-Flo Estrogen cream and their Bi-Est (Estrogen plus Estriol) before for nipple growth, but it did not seem to give me the results I hoped for.
So I recently acquired some topical (vaginal) Premarin cream, and applied that along with some Supple Cups to hold it in place. And wow, both of my nipples are wider and unmistakably non-masculine. The areolas are a little bit larger and darker as well. There are Estrone-only creams that may achieve the same results but I have not been able to find a source.
Disclaimer: Premarin pills may work for this if you make your own cream, but general consensus is to avoid Premarin pills taken orally.
Edit: I'm using .5mg of the cream across both sides, and taking 81mg aspirin along with it.