I was looking for ear tips that can store more than 6 pairs but I haven't found one, so I made one myself, it is about 141 x 101x 16mm that can store up to 45 pairs of ear tips. It is also a sliding case design with a recessed handle for easier handling. I haven't printed it yet although I'll share it for anyone to use.

Update:

Added Slots for 4x1mm neodymium magnets for a locking system. Not experienced in making locks but this should work with this design.