I thought I'd try sharing some more shrinking scenarios, but with bad endings just for a change of pace:
1. A witch, her warlock husband, and their four young girls (all between the ages of 4 and 12) are practicing nudists and have gone to spend the day at a secluded beach.
The witch and warlock are trying to be intimate with each other, but the four girls keep ruining the mood; wanting to get the girls out of their hair, the witch tells the girls to go explore the beach on their own and hastily casts a shrinking spell on them to make it "more exciting" per their request.
The girls, already visibly shrinking, all run off to leave the witch and warlock to fool around without any distraction.
As the girls play and roll around in the sand, they continue shrinking smaller and smaller until they're all only about 7 or 8 inches tall; at this point, they decide to go back and pester their parents, not realizing that they're still slowly but surely shrinking as they make their way back.
By the time that they've made it back to their parents (who are both now asleep after having the most intense sex they've had for a long time), the four girls are now about 3 or 4 inches tall.
They crawl and jump on their mother to try and wake her up, but she doesn't stir; the girls decide to just have fun as they keep shrinking, moving to one of the mother's now-gigantic breasts to bury their increasingly smaller bodies into her magnificently soft and fragrant flesh.
The girls laugh and cheer as they completely shrink from sight just as the mother finally wakes up; the mother is shockingly not that bothered about what, merely shrugging it off as her still not being very good with that spell.
She wakes up her husband and tells him about the mistake, but he also merely laughs it off as her needing more practice; after having sex again, the two wonder out loud how many daughters they've lost that way (and how many are probably living as microbes on/in the mother's body).
2. A young girl has the strange ability to "transfer" herself into any human-shaped simulacra like statutes, dolls, and figurines, wherein the object turns into an approximate physical likeness of the girl (even somehow becoming anatomically correct and being capable of sensation).
One of the girl's favorite activities is to transfer herself into her favorite ragdoll, disrobe, and masturbate to her reflection (sometimes even using toys and doll accessories as makeshift dildos).
Wanting to experiment, the girl soon tries transferring into new and riskier objects including a small porcelain doll with a removable dress and an even smaller wooden doll in her dollhouse (with the girl amazed to find that she could actually take off the "clothes" carved into the doll's body).
Being so small and literally walking around inside a dollhouse is utterly intoxicating for the girl, who now spends entire evenings by herself in the wooden doll's body (even making and pleasuring herself with numerous "husband" dolls).
While out looking for more doll accessories, she stumbles on a tiny "dollhouse" prop that fits perfectly into her own dollhouse.
After the girl puts the teensy dollhouse into the larger dollhouse, she transfers into the wooden doll again to admire it closer; she's not only amazed to see the tiny dollhouse can be opened, but that it's actually a tiny music box with a miniature ballerina figure inside.
The girl, now practically insane with lust over the possibility, attempts a secondary transfer from the wooden doll into the ridiculously tiny ballerina figure.
She has to put an immense strain on herself to do it, but pulls it off: she walks out of the music box (which she put on the floor of the dollhouse's upstairs bedroom) and strolls around at the relatively size of a doll to the larger wooden doll.
However, she begins to feel really drowsy and disoriented, goes back to the dollhouse bedroom, and climbs up into the doll bed.
She then takes off the ballerina outfit, props herself up against the bed's tiny pillow accessory (that she's now even smaller than), and vigorously masturbates as her mind becomes cloudier and cloudier.
The girl soon falls into a deep slumber following an explosive orgasm, becoming fully inanimate and permanently trapped in the ballerina figure.