A gimlet? Hammer and a thick-ish nail? Honestly I can't remember how we used to do it. Might even have used a hand drill at some point. They're fairly soft when you've made a hole in the shell, so you might get away with a screwdriver?
When at school we probably made do with a compass (the drawing kind), as we all had them. I'm sure that resulted in a pretty high rate of conkers being destroyed before they could be strung, and a lot of ruined compasses.
> Also, doesn't the conker spiral around your hand hitting it and hurting you?
Generally not, though the game isn't without its minor hazards :)
We used to have a BBQ skewer that we used for various purposes, including adding holes to belts. We'd heat it up on the gas hob and then burn a hole through the conker. I actually still have the same one I've inherited in my kitchen drawer. If you have an awl, you could use that instead, but I'd recommend heating it to get a cleaner hole.
You need to use a long enough string. Old cotton shoe laces are actually perfect as the aglets make threading that much easier.
The force of one conker against another is enough to sometimes make it spin round, but not enough to do any real damage. You just need a long enough string that your fingers are not in the firing range. Obviously there is a vanishingly small risk of a piece of conker ending up in the eye but I never witnessed that or any other injury happening. The biggest problem was usually upset kids when their prized conker got destroyed.
I'm not from Britain, but we used to craft with chestnuts. We always used a small hand drill (Wikipedia tells me it's called a gimlet). I assume it's the same in Britain
The memoir Where Did You Go? Out. What Did You Do? Nothing describes using a heated icepick.
You take a chestnut, and you hook the ice pick. You wait until nobody is in the kitchen, and then one kid presses down on the pilot-light button so that a long delicate blue finger of flame comes out, and the other kid puts the ice pick in the flame until it is red-hot. When it is, he bores a hole in the chestnut. You do as many as you can until somebody comes and asks you what you are doing, and then, according to your standing in the family, that day, you either plead, argue, or say, “Oh, jeez,” and slink away.
> Also, doesn't the conker spiral around your hand hitting it and hurting you?
Not usually in my experience, the string isn't that short and you're holding it at one end. Injury is still possible though, but that's part of the fun!
We've got a ton of horse chestnuts in my neighborhood but I've never heard of this game and I'm eager to introduce it to my kids.
Also, doesn't the conker spiral around your hand hitting it and hurting you?