A few ideas come to mind while thinking about a cave.
An mine elevator
Crystals
A minecart
Fallen rocks blocking a path
With these ideas I made a few different sketches trying out the possibilites for a puzzle.
This is the final sketch of my puzzle. It will use the elevator idea. The elevator has lost its power and the player needs to turn it back on.
After the final sketch I felt like I did not have enough research of the interior of the caves. I made 2 small moodboards with different cave interiors and layout, which helped greatly for making the concept art and also making the models in the production fase.
These models are mostly human made structures using wood and metal.
These sketches are the base of making my blockout, they help creating the atmosphere and base layout of the puzzle.
The only thing this puzzle cannot provide is accurate spacing between jumps. This has to be tested inside of Unity after placing all the colliders.
While making the layout of the puzzle it was also important to know what the player will actually see. The red rectangle will be the view of the player. This shows that the player will not be able to see all the puzzle elements at the same time, which will force the player to explore the map.