You can't really 'make' sea salt - it naturally occurs in sea water! But you can extract it. I'm probably kidding myself, but it seemed to taste better as well. :)
Step 1: Get That Water
In Britain we're never more than an hour or two from the sea. I was visiting two of my daughters in South Wales and collected to large milk containers full (about a gallon). I collected it from some puddles as the tide receeded. This meant the water was not turbulent so I could avoid gathering sand or other bits. :)
Step 2: Pour Some Into a Saucepan and Heat
I had the gas down low as I did not want the bubbling to be too furious. Keep topping it up every half-hour or so. Gradually the water evaporates.
Step 3: Keep Going!
After a while all the water starts to become cloudy with the salt. This pic is how I had to have things set up (and try and cook at the same time!)
Step 4: 8 Hours Later...
All that water has been reduced. We're nearly there, but now we need to pay more close attention to avoid getting the salt stuck to the bottom of the pan. It's just a question of heating and stirring...
Step 5: And Finally...
you'll end up with a pile of salt. I got 181 grammes or so.
Step 6: I Did a Video As Well
I'm sure a sensible person would do this much quicker than me - larger surface area + sun power? Maybe next time. I'm glad of the 'free' sea salt (no costing for the gas!) and it seems to taste the best ever. :)