If I need to make a dripper at home I usually use a half-liter bottle of milk really well washed. With a push-pin I will make holes on one flat side/the bottom with just the thinnest tip of the push-pin, to get a slow drip. If you go all the way through with the whole thing the hole may be a little too wide and you'll end up with a thin stream. Then I make an air hole on the opposite end.
Then I fill up the whole thing, screw on the cap, and rest the dripper on the cage. Depending on the number of holes I either have a rain effect or just one or two slow drips for hours. And the air hole on the opposite side helps fill in the vacuum with air, so it doesn't stop.
That's my version of a cheapo dripper, but you can certainly buy one if you feel more comfortable doing so.