In hockey (*field* hockey if you're not English), I spend a lot of time running after the ball after it crosses the sideline, only to run back to take the sideline hit from where the ball first went out of play.
There is a straight wooden boundary on most pitches, usually made from railway sleepers,
usually about 3 metres outside the dead ball line. However, as the ball rebounds off the sleeper and continues rocketing up the pitch, it's not a very effective barrier.
I propose the "zigzag sideline", replacing the railway sleeper boundary. It would have two improvements. Firstly the material used would have 'deadening' qualities, taking much of the speed out of the shot.
Much to the joy of most 'bakers, I have a hunch that a custard filled object might be useful.
The second change would be that the barrier would be zigzig shaped, so the ball would be rebounded (generally) back onto the pitch nearer to the position it left, regardless of which direction it was hit from.