Sorry, but I have to ruin the party...
It looks pretty simple - and I would sure have done it something like this. But it wont work.
The capsules are not cubes, not square at all. They are more like "balls with edges". They are round on the back and have a flat, round front. Check out the Nespresso link I posted. They wont stack proper and will block in the pipe.
Most capsules holder are build something like this:
Swissmar Capsules Holder @ amazon.comI thought about something similar, with 2-4 "tracks" and a bit of space for a scroll saw pattern... but could not come on with a good solution. The tricky part is the capsule track - it needs to hold the capsule, let it slide down and must have a bottom ending, which allows to take a capsule out...
regards
Torsten