Getting locked in some kind of fetish garment, or more general, just not being able to take something off. That could be done with actual locks, or glueing something closed, or just actually getting sealed in something, that when dried / finished processed, has no opening. The tag Chastity is always combined with this of course.
The Itch That Could Not Be Scratched by Darkthoughts
The Itch That Could Not Be Scratched by Darkthoughts (Archive Link) This is one of my favourite bondage / fetish stories ever written. It has a bit of everything and actually introduced me to the Medieval Dress concept for bondage purposes. The story follows Caroline having an encounter with an ex-prisoner she had put away. The prisoner, Gold Finger, wants some revenge and kidnapped her sister. He offers Caroline to let her sister go, if she accepts to become his personal slave for an entire month. Very reluctantly, Caroline accepts, but she didn’t expect how far and extreme Gold Fingers slave-training would become… ...