I found rearing my kids not to be complete arses was the best solution, and is far better than any kind of physical preventative measure that you'll then blame when it doesn't work or when they learn how to circumvent it. The one at 15 is already more than old enough to know better, and the seven year old is at the age where you should already be teaching him/her to know better.
I had twins so I know how hard it is to raise kids, by the time they can move on their own everything is suddenly a threat or a weapon. You're trying to stop one of them bashing their own brains out with some innocuous ornament in your living room you never even considered before to be a danger to life, while the other one's toddled off into the kitchen, emptied half the kitchen cupboards and is busy twatting the cat with the frying pan.
But no one said it was easy.
That's probably a terser and less helpful answer than you hoped, and for that I apologise.