My suggestion is a buyable DLC named Clockworks Creator. It is a very simple editor that lets knights manipulate the clockworks.
Once one has bought the DLC, they would need to enter a new gate with a screen showing a purple gear logo.
They can only interact with the panel in the gate once they bought the DLC. If they do, they will have the oppurtinity of clicking a "Go" or "Stay" button.
The Go button will make you go to a room with Intel Agent Kora or another familiar-to-everyone character.
Stay button will cancel going to the editor. When they arrive for the first time, Kora explains them the Gremlins at Emberlight helped Spiral HQ by providing them with a device that somehow lets them create new levels in the clockworks. The gremlins however do not know if it will be useful for us in reaching the core.
---
How it works:
Ever saw the Portal 2 PeTI editor? Well, this editor shall be as simple as that one, or simpler. One could change the Background, Tile set (or use multiple at once if possible), monster spawning locations, and entities (team button, etc.). The revives in the player-made levels will cost 10 crowns per party, 5 per player, and would land in the owner's pocket.
The editor would have access to monsters who aren't seen in the clockworks anymore, such as the Tortadrone or Green Jelly Giant (and possibly Vog cub if those are still in the files? :D). The editor however, wouldn't have access to the energy toll gates. Instead, theres a 2 crown tollgate. All levels made by players would be located at Depth ???.
---
Gameplay:
The If the player goes to the room with Kora, and interact with a panel-with-elevator, they will see a browser of levels made by other players, with a Reputation Ranking. A player can give 1 Reputation Ranking to a level after they completed it, with the owner receiving a random amount of crowns/random materials per 30 points. After completing a custom level the player(s) will have a very small chance of receiving a Mini Mist Tank or 2CE for their "bravery." It will be like the Prize wheel, except with lotsa empty slots (By that I mean more than normal) and 4 with the rewards: 2 mist tanks, and the CE.
The enemies will have a very, very, very and once more very small chance to drop 1ce (And they never drop anything besides that). This is to prevent people from making Crown Farms. And in order to prevent too many of these custom rooms, there will be a limit of 25 (Or less) levels per knight (Not account.)
And to forcibly force the players not to make lotsa rooms, there would be an additional CE & CR fee per room made (Similarly to guild creation).
This DLC would have 3 missions:"Meet Kora" (Go to Kora's location, the editor hub room and talk to her {she shows/tells how to use the editor/browse trough levels}) "Playing With The Clockworks" (Objective: Make a level and publish it.), and "Visitor of the (un)Friendly Worlds" (Beat someone's level and give them a reputation point).
PS: I probably aren't the first with a level editor idea, but I am the first with the sub-ideas of the idea!
PPS: Please comment on this, what should be less, what should be more? :)
PPPS: Read it very carefully, if you didn't.
This can be abused way too much. There seems no real limitation at what you can do and what not, and if the other people's CR lands in your wallet as soon as they enter, you'd technically just have to make an impossible level, let them revive a bit, and leave them out in the open, with you chuckling evilly. These seem like small amounts, but it's technically still money you get for free, and we don't know how many people will be using it. Not to mention it would be spammed with millions of stupid, uncreative levels and stuff.
Not too mention that in my honest opinion, if there's some sort of feature for community-creations, then it should be definitely free, because creativity shouldn't be a DLC, especially if it could potentially help to increase the games size which is, admittingly, still pretty short on content, with repetitive clockworks, lousy endgame and most importantly, completely imbalanced CE-price that's already going to hit the fifth digit if something isn't done against it that persistently makes crowns more valueable(because if people can contribute to the game, one of the first things they'd be doing is adding several ways to make arcade profitably playable and MUCH more ways to waste overabundant ressources. The gate creation-suggestion comes to my mind).
In other words, if OOO could create some sort of thing where the community can contribute to the game, they should do it for free, because it benefits them, the game and the playerbase that really wants to contribute to the game.