BiB - Ariel in a confining blue jumpsuit
A while ago I found a jumpsuit on the Internet that really suited my fetish: not only did it close around the neck with a chain - that's asking for adding a padlock in my book - but it also had straps limiting the upper arms. (ChainedUp Jumpsuit at Revolve) The price was way too hefty for me though, but then I found a cheap rip-off at eBay (brand: Mystery Jane), with the additional benefit that the fabric isn't stretchy. Only the 'shoulder' straps are.
To make it more confining, I added non-stretch fabric under the 'shoulder' straps, and when Ariel put it on, it really kept her upper arms close to her body. (See for instance the dent the straps make in her upper arms in photo 3 and 4.) So much so, that she couldn't even operate the zipper: she could reach the pull, but not exert downward force because with her elbow close to her body, her hand would move more sideways than down.

She could also reach the necklace clasp with one hand, and although it was doubtful whether she could operate the fiddly clasp that way, I 'helped' her out by adding a cute little padlock.
Ariel is rather tall, so I was pleased that the length of the jumpsuit was OK. Still it pulled a bit at her neck, so afterward you could see the marks the chain left.