From probably around ages 8-13 I kept a large cardboard box my family got a package in in my bedroom, and every day after school I would toss in a blanket, reading light, and book then stand on the foot of my bed and hop into it (the only way I could get in with it standing upright) and then close the top above me and hang out in there for hours reading. To get out I would just push my weight to one side so the box tipped over with me in it and then climb and out put it back upright for the next time.
I controlled the light, I controlled how warm I was, and since the box was just big enough for me to sit in with my knees to my chest (it was probably ~4ft tall with a 2x2ft base but I was a pretty small kid) I could feel all 4 sides and the bottom and would immediately know if someone opened the top from the light, so I know no one could see me and could sit/act in a way that was actually comfortable for me (I was used to constantly adjusting my behavior to be socially expectable at all times because I was afraid if I didn't someone may be looking at/watching without me realizing and judge me for acting 'wrong' (I didn't know about the concept of masking at the time but I sure as hell knew how to do it). 🙃
I adored my box and still think of my time in it as one of my most enjoyable/positive childhood memories.
Whats that? Oh no, there were never any signs I was neurodivergent as a kid, why do you ask? (/s)