Most people can't lift out of a box with only their hands.

Here's an interesting idea. If you have a sturdy box big enough to fit your legs inside while folded up and as long as it doesn't fall over it is nearly impossible to escape. One cannot use their knees to push themselves out of a box and lifting yourself out of one by your hands requires some really strong upper arm strength. This seems like a godlike way to cheaply and easily keep yourself locked in if you have the front or back panel removable/hinged to let yourself out.

This has been a fantasy of mine for a long time, but with the legs in the lotus pose.
I just have not yet found a box in which I fit in

[Like Ra]

the legs in the lotus pose.

And this is one of my dreams 😉

We tried that in the army (quick securing of captured enemy). Actually, we sat someone with his legs around a small tree and pushed him down for a minute or so. He was clearly unable to stand up, but begged us to get him up quickly, because it hurt so much. Not my cup of tea!

Sorry all, but I have no idea what a lotus box is.

Picture, maybe a description ?

No, not a lotus box. Simply a box where you can just sit in with your legs crossed.
Lotus came from Mat.Mardigan's idea to sit in a lotus position, which means to have each foot on top of the other upper leg. It is a yoga position, also Indian meditation seat (the posture, not the wooden box, which has nothing to do with "Lotus").

[Like Ra]

Simply a box where you can just sit in with your legs crossed.

I think not even crossed. Just a simple "seiza" (Japanese martial arts) or Vajrasana (yoga).