Let's draft together a block for a corset with cups.
You can use it as it is for a top or bodice of a dress, or you can use it as a foundation corset in more structured dresses, as bridal ones.
In any case, we suggest to start from a basic block with darts and ZERO wearing ease (i.e. your exact body measurement, taken wearing only a bra). Also, we recommend to always make a muslin/toile to fit the garment, and this is especially true in this case. The muslin should be done with staytape at the neckline and underwire at cups (also foam if you plan to use it in the actual garment).
We suggest to use a non stretch fabric with lightweight interlining (fusible knit interlining or lightweight organza if you like non-fusible ones).