Reversible Gear (2in1)

Reversible Gear is a reconstruction of the level of the same name in vanilla Super Monkey Ball 2. It is the 28th stage of Advanced for 2in1. Reversible Gear is infamous for being the first major wall for many first time players, due to the significant amount of trial and error involved, and general intensity of getting into the goal, with no chance of being able to survive if you enter the wrong hole or mistime entering the right hole.

Description
A large gear with eight teeth rests and spins on top of an octagonal platform, not unlike a starfish. Every five seconds, the gear will make a full rotation and a half counterclockwise, then it'll spin clockwise back to its original position. One of the walls of this gear is removed leading to the inside of the gear, which contains the goal. There is a single banana outside of this hole, while all of the other slots in this gear have banana bunches. The player starts in front of this setpiece.

Goal tutorial
From where you start, there are only two faces of the octagon that the hole will point towards: Either the bottom left, or the top right of the octagon. The easiest way to beat the stage is to head over to the bottom left of the stage, face the gear, and wait until the timer hits 51.5, then charge straight into the gear. Because the goal rotates with the gear, it's easy to get disoriented as the gear is rotating and it's also possible to be spit back out of the gear (and most likely, to your death) if you get too close to the exit of the gear. Try to pay attention to the checkers on the floor to keep yourself oriented, and then break the goal tape. If you decide to enter the gear from top right area of the stage, you'd charge inside the gear at 46.5. Since the stage is on 10-second cycles, this means you have six chances each to get inside of the gear, with the bottom left opening appearing every X1.50, and the top right opening appearing every X6.50.

Differences from vanilla
Gameplay wise, the only difference is that the starting platform doesn't exist and the player starts on the octagon. This is actually very significant as this means the stage can be beaten in a whopping 5 seconds, which not even the fastest time record for the vanilla Reversible Gear reaches. This can be done by heading towards the top right of the stage immediately and turning left at 56.5. The gear itself has been given transparency to make it easier to see where the opening to the gear is.

Trivia

 * This particular reconstruction is the first custom level to have actual stage transparency and shadows. Before this, real-time shadows were non-existent in custom levels, and transparent objects were usually broken, in that you couldn't see any placeables, the monkey, certain stage objects depending on the stage's object order, or even the BACKGROUND behind them. The initial workaround to this was to misuse the meshes for game objects such as goal frames and switches, but this came with downsides such as not being able to see other transparent objects through meshes. The way to obtain these effects was to identify the pointer for the level model in the StageDef (the uncompressed .lz) in a hex editor and change the eighth zero in the first listed field depending on the effect you wanted (1 for casting a shadow, 2 for receiving a shadow, 3 for both, 8 for being transparent, 9 for being transparent + casting a shadow, A for transparency+receiving, and B for all three), which was something the modding tools at the time didn't support. Since then, the modding tools have been advanced and plenty of levels with shadows and working transparency have showed up since.
 * The gear was not originally intended to be transparent. That was a leftover for testing proper stage transparency that never got fixed before the final release.