Black Box

Drop me a hint, I even saw a ball rolling out of the gate but only once.

Spoiler: What the heck

A few tries later the ball pushed the wall down ,but I don't know how the ball reached the pushing element ?

@Rohan Kumar

Spoiler: Hint

Moving the top lid will drop the ball which in turn will automatically cause the side wall to get pushed out.

Full solution. I would suggest only peeking ahead if you get stuck.

Spoiler: Getting the bot off the box

Find the highest draggable in the structure and slide it all the way through. Note that a piece will fly off the other end. You need to put B-Bot on this piece first. Restart the level and put the bot on this movable block. Gently move the slider through until you see the block with the bot on it move, then jam it through. The piece should fly off and B-Bot will fall to the ground.

Spoiler: Unlocking the gate

You need to first "Unlock the Gate". There is a draggable block with a metal cylinder facing downward. You need to spin the cylinder to that it is facing upwards. To accomplish this, jam the lower draggable that is just inside the box up and down. It helps you're not looking at that face of the block from an angle. The cylinder should spin about, but will likely take some tries. Once the cylinder is facing up you're all set.

Spoiler: Getting the bot inside

There is no place where you can select a focus spot inside the box, but if you raise the gate up (the draggable block structure with the cylinder) and move the bot under it, he'll walk in using the low-ceiling exploit. Once the bot is inside, lower gate then tap on the cylinder. B-Bot should walk there via a tight spiral staircase.

Spoiler: Step #4

Removing the lid. With the bot on the vertical cylinder, move the draggable right behind him up and down. You should see the bot bounce up. Launch the bot up, but not too high. While he's in the air, pull the horizontal slider out (i.e. the one used to get B-Bot off the top of the box). With a bit of luck and skill land B-Bot into the slot in the slider. Gently move the slider with the bot in the slot to remove the lid with the Bot's eye. If the bot starts slipping under, pull the slider out to let the bot stand again then continue forward. Occasionally the lid can get a little stuck as it angle upward, if this happens make the bot walk out along the slider then jam it further in and hold it. If the lid turns diagonal it's likely stuck for good and you'll need to start the level over.

Spoiler: Step #5

Nudging the lid drops a ball into the moving slider, which in turn pushes of section of the side wall out. There is a draggable block on the wall piece which fell out. Use the draggable to move the wall piece (which is now lying flat) such that the right side of the wall piece is now flush against the middle of the open wall space. This forms a bridge that the bots can cross into the inner part of the box.

Spoiler: Step #6

Look into the right side of the inner box you'll see a ball up on a cylinder. Make B-Bot go knock that ball into the hole to the right of it. You need to have B-Bot nudge R-Bot onto the fallen wall to get B-Bot past R-Bot.

Spoiler: Step #7

In the right hand side of inner space is a draggable, move is as far left as you can. This clears a path for R-Bot to go through. Next use B-Bot to nudge R-Bot across the fallen wall and down the steps into the inner space on the right. When R-Bot is down there move the slider to the right to force him up to the right hand side platform. He should then walk across the ball you knocked in and will pace along the wall.

Spoiler: Step #8

You then need to use the same slider that you pushed R-Bot up on the right hand side inner platform to get B-Bot up there too. When R-Bot walks to the far back wall, move B-Bot to the top of the ball. R-Bot will turn and walk to the Win block. Done!

Spoiler: Notes

The draggable in the wall connects to the wall via the black stem of the motor. Without the motor you could actually just pull the wall out even without seeing the draggable. Also the motor-draggable connection made this free block far more controllable. Without the motor, the wall was just about impossible to control.

Ahhhhh..got it now. It's a great design. I like unlocking things. Before seeing your steps, I was stuck. Because the top lit was not fully opened and I didn't know is it suppose to be like that or not. This level got a lot of steps. orz. so tired. At the end, I push them two next to the win with the side lit to solve it. I gave up.-0-