Chainmail provides little to no protection against impact damage. As we saw in Fellowship, evil beings who attack heroes in bed use slashing attacks with broadswords or similar weapons. While it might prevent cuts, it’s basically like being beaten with an iron rod that will break bones and rupture organs. It is unsuitable as armor. That’s leaving aside weapons like maces, hammers, and clubs, or a Seal Team Six scenario.
It’s aluminum. Or aluminium, if you’re that kind of person. This is basically a blanket designed by Jony Ive. It doesn’t warm. It doesn’t protect. But it’s thin and lightweight. Which is the opposite of what you want in a weighted blanket.
You can buy weighted blankets that come in a variety of weights and warmth characteristics for a fraction of the time investment used to make this. The money you save could be used to buy a home security system that includes a minefield or electric fence. If you’re impressed by what a claymore sword can do to an orc, wait until you see what a claymore mine can do.
I know #1 is a joke but for everyone else in history that's why people wore the aketon, or gambeson or padded/quilted tunic under mail. Provided impact protection and made mail more comfortable!
And the combo of padding + rings was more effective against cutting and blunt weapons than either on their own! And it was easy to maintain, repair, and the mail could be transferred from person to person with some addition or subtraction of rings.
Claymore mines are terrifying. Most commonly, though, they are used in large open areas and may be problematic if your home is not rural.
Claymores fire steel balls at a wide 60 degree angle. It's stated that they are guaranteed a kill at 50 meters but can still be dangerous out past 150 meters.
While claymores are often depicted as being laser or tripwire activated, they are most often activated using a clacker detonator held by an operator. They can be rigged to detonate via both electrical and mechanical means, so they can potentially be activated by a variety of methods.
Literally anything you can DIY yourself can be bought at a lower dollar and/or time cost. That's not why people make things.
There are many reasons why people make things, but generally speaking it's because you can make exactly what you want, in terms of size, material and design.
It's fun, interesting, you learn stuff, and you get the joy of doing. This guy didn't want an off the shelf weighted blanket, even if it is cheaper/easier to get/whatever.
Sometimes, when you make things, they don't work. Or you realise that you made the wrong thing, or made it the wrong way. But that's when you get the buzz of knowing that you learned something, and the excitement of planning how to do it better.
Knitting takes a long time and the yarn usually costs more than a machine made version would. But I have friends who still have beanies and scarves that I made them 10 years ago when I was learning to knit. Why? Because they know that I made it for them, which gives them feels.