This is only an idea, but the idea is, that when moving the brown piston
downwards inside the cylinder, the (blue) breast cups will suck at the breasts,
and simultaneously the (light blue) dildo will grow.
The breast cups are made from e.g. Polycarbonate or another 'hard' &
transparent plastic, but the dildo is made from e.g. latex or another highly
flexible ( and thus inflatable- ) rubber.
Maybe it will prove a necessity to have two pistons, one for both the breast
cups and one for the dildo, but none the less, I think that the idea will
work, when constructed in a proper way...