Thick plate joint filling
If the gap is very small, thick plates can be used to fill the gap, which is easy to solve the problem.
Custom lockers
If the gap is large, you can ask the carpenter to customize a locker, which can not only put decorations, but also prevent items from falling into the gap.
Adjust the position of the bed
If you don't want to seal the gap, you can change your mind, install a countertop or adjust the position of the bed, which can not only solve the feng shui problem, but also increase the storage space.