Here are some hints if you need them: Spoiler: Hint 1 look for visual clues on the 3rd side. Spoiler: Hint 2 hidden doors will take you to the opposite side Spoiler: Hint 3 use the red robot on the 4th side to drop a ball (Edit) Wow! Thanks for all the positive feedback! I didn't know that I made such a good level. I'll try to make another one of the same quality.
Welcome aboard. Talk about your first level, Wow, very amazing, it's like turned around the cave with some challenges. I like the hidden doors, and the last part. Great cave level, thanks @Kaycal (Six star for you)