You don't have to trap your kids in these gates and then charge admission while selling sno-cones, but you can. That might be illegal. Actually, yes, that's very likely illegal. But if you want to try it, here are the gates and fences that could do the trick.
It's a simple story: there was a guy named William Lockett III, and he loved making gates, so he started selling them. There's no elaborate spell involved or quests through cavernous valleys and across barren wastelands. Just a gatemaker and a company that likes to sell safety products for kids.