So many options! Probably the purest form of the fetish of having a transforming partner, fantasizing about slime girls can go in many different directions.

For those who emphasize the slimy nature of slime girls in their fantasies, having the smooth and fluid texture pressing against your body would feel great. Goopy hair and features while never quite being in a truly solid form adds to the unique experience. The infinite supply of lube is another big plus.

The flip side is the amorphous form of slime girls, who could turn into doppelgangers of anyone or grow various appendages. Anywhere on her entire body can act as an orifice, or you could have parts of you enveloped inside her while she plays with you through different densities of slime, like getting a handjob underwater.

Another fun aspect is her transparency. From seeing yourself through her or watching as you fill her womb, to watching her change from clear to milky white after you finish in her.

More esoteric fantasies could involve absorption or vore, or using her insides to transform others.

More playful and less overtly sexual scenarios could involve imagining how her having a body made of slime plays out in other aspects of life. Does she sleep in a bucket as just a puddle or blob? Can you take a bath using her as the bathwater? Could she change color depending on her mood?

What sort of fantasies do you have about slime girls?