Best way for optimizing area/volume occupied

Hi, been working on a problem that requires to efficiently pack some objects.
What would be the best way to minimize teh space occupied?
I have been trying Gradient Descent based technqiues for minimizing the bounding box size of the objects.
- Gradient descent might not be best approach here.
- bounding boxs are parrallel to unity axes (so cant account for rotations and weird objects).

Any input is appreciated

Thanks
Krishnan