Thank you, @Magpie, @AIMR, @gozer, @kittykill and @MegAskunk!
They would make nice hackey sacks, but with the plastic ball inside they are too light. I’m not sure if they’d hold up a nice shape without the ball. I wrote this pattern specifically for covering the plastic ball.
My other crochet ball pattern (stuffed ball crochet pattern) might work for a hackey sack, but only if you use thin yarn, otherwise it’ll be too big.
For those of you that are going to buy pit balls, please note that they come in different sizes! This pattern calls for 7cm ones.