How difficult is a tit job in TPE/silicone?

[TPEsnack]

My friend's gf just had a tit job. No, not the usual way, the opposite way. They were, apparently too bulky and heavy.

How difficult is it to learn how to adapt a doll's breast cup size? Are there particular manufacturers or materials (e.g. TPe, silicone) for which tit jobs are easier and more successful? Does anybody do this as a business in Canada?

Presumably there are technical limits, such as going to AA is too difficult due to internal structure.

I see this as a technical/artisan solution to the plethora of D+ cups that are popular on the market.

Yes, I did some searches on breast reduce and similar words and didn't see anything listed.