I Ace and collect all of the single-player Goodies in the "The Construction Site" level.
Of the three "The Metropolis" area main levels, this one is the only one that I can claim to like. None of them are bad and all three have their enjoyable moments, but I find that "The Construction Site" is the one I like most. I think it is because it is so expansive in comparison to the claustrophobic previous two locales. Also, the song 'Atlas' by Battles features prominently in this level, and it's one of my most favorite licensed tracks used in this game. (If you like the song, you should consider checking out what the actual lyrics are. Quite interesting, and it's nice that I'm no longer stuck guessing and using mondegreens when I try to sing along.)
I apologize for taking so long to get the Challenge Key in this video. Sometimes I can get the tipping going to the point where I can get to the top beam quickly, but other times I seem to struggle and I'm not sure precisely why. Just keep your determination and persistence up when dealing with this Key.
I've always found the Ze Dude boss battle to be one of the more interesting ones in the game. If you're accurate, it's actually quite easy to nail the preliminary Bouncers before they've gotten through one firing cycle. I got the second Bouncer this way, and I just barely missed getting the first Bouncer with a very similar method.
Also, for the boss battle and as shown in the video, I highly recommend that you stay to the right of the launching platform. I find that it is much safer when you are dealing with both Bouncers, but its security is compromised as soon as the platform starts tilting.
The third stage of the battle (Ze Dude himself) isn't that difficult, but the tilting platform makes it more difficult to get the right angle and speed for launching the projectiles back. It's also quite possible to nail him fairly early on in his firing cycle, but I just missed multiple times and only got him later on.
Revisit: No revisit is mandatory, but I separated the Cooperative Challenge area from the collection of single-player Prize Bubbles to make it easier on myself.
This video covers the Cooperative Challenge (and its exclusive Goodies) in the "The Construction Site" level. Since they are both fairly easy to pull off, I show both the "improper" method for getting the Goodies (in which only one player is needed) as well as the "proper" method using two players.
Special thanks goes to the random online player featured in this video. She goes by the PSN ID of bigdogstompin.