Beautiful Katamari

For this achievement, you have to crash into a wall 30 times in a single stage.

I would advise doing this once you have unlocked the eternal mode for a level. To unlock the eternal mode, score over 100 points in that level. After you have crashed into a wall 30 times, you can exit the level by pressing X.

If you want to be extra efficient, you can do this achievement while earning this one (dash 30 times in one level):

What the two other solutions neglect to tell you, is that not only do you have to crash into the walls 30 times, stuff has to be bounced off your katamari. So rolling into a wall before you've rolled over anything won't do you any good.

I recommend doing this on a time trial since that's basically endless too, plus you probably have access to time trials before you have access to eternal modes. The "Chatéau Notre Desir" solution also doesn't work as once the game stops asking for memories, you've most likely grown way too big to be able to crash into walls anymore.

This Can be done in the Chateau' Notre Desir. This is the level where you re-roll Uranus with no time limit. Just wait until after they stop asking for memories and do the 30 crashes and press X to end the level. The achievement will pop after you get all your presents and cousins.

I actually got this accidentally on the mechanical DLC stage.

When you're small, it's easy to get bumped around on the conveyor belts on that stage.