First, obtain some pork rind. This is probably the hardest part of the process. My own local supermarket (Morrisons, for those of you in the UK) happens to sell it, in among the joints, for extra crackling; I buy it when I see it, and freeze it against a need.
The only ingredient else is a herby salt. I mix granular sea salt with herbes de Provence or erbe di Siena; Lakeland sells a pre-mix called "Good With Everything", which is also good.
Now you need a sharp kitchen knife (sharp, please) and a baking tray.
Light your oven and let it warm. Meanwhile, lay out your slab of pork rind rind-side down, and rub your herby salt into the fatty side. If the salt's at all fine, be abstemious; I'm quite generous, but the salt I use is like hailstones, and half of it goes pinging off in the process.
Now roll up your slab of rind with the herby fatty side on the inside, and slice it into fingers (I did ask for a sharp knife, remember? But it's actually easier to cut through in a roll).
Now lay your fingers of rind on the baking sheet, fatty side down, rind side up. Turn the oven to the lowest possible setting - really truly - and slide the tray in on the bottom shelf.
Close the oven door, and leave it.
Do all this in the morning, and leave it till the evening. Eight hours is certainly not too long.
You will find that some of the fat renders out (yay! it's healthy!); you can drain that off at this point.
Now turn the oven up to middling-hot - gas mark 5 or 6 - and put the tray back in at the top of the oven.
Now you have to keep an eye on it, because over the next twenty minutes or half an hour, that pork is going to scratch.
There are three stages to this, and only two are desirable.
First, your dried-out but still floppy fingers are going to turn stiff and crunchy. This is good.
Second, they are going to pop like popcorn, turning light and crunchy and lacy inside. This is better.
Third, they are going to burn. This is not good at all.
The trick, obviously, is to catch them between stages two and three. You have perhaps five minutes.
They'll probably curl up; they may go three-dimensional. Catch them while they're still golden-brown, before they go black - but try not to be pre-emptive, don't lose your nerve and take them out before they've popped. That way lie broken teeth, as you discover bits that are still leather at heart.