This system can be used to store Nespresso capsules under a shelf. You can have the capsules hanging over the coffee machine. The holes in the holder are in an angle, so rail is tilted. This makes the capsules move to the start of the track by gravity.
You need to orient the parts before printing. Flat the rail on rotate the holder so that the holes are upwards.
Then just insert the rail to the holder and then screw the holder to the shelf. You can put multiple units side by side. They have alignment features on the sides.
The capsule is also included if you want to design something yourself.