You’ve tied single and double column ties, and tied those to something solid, now lets do something ‘on the body’ with that; lets tie the hands into a chest harness

First start with a single or double column tie (as you’ve done previously) and sit or stand your partner with their back facing you.

Now take their wrists above and behind their head.

Now form two bands around their torso, just under the nipple line.

Finish with an x-friction and a half hitch (the x-friction really is optional, but this tie is a good opportunity to practice it)

Note that the pictures shown here does, in fact, show a single column tie being used, not a double. Both can be used here safely here, but the double is more secure/less likely to allow your partner to slip free.