I suspect this is a pretty hard problem if we are allowed to tilt the cylinders, so I also offer the easier problem: What is the smallest cubical box that will fit n cylinders, each parallel to one of the sides of the box?
Here are the bestknown packings of tuna cans. For each, a 3dimensional view and a top view are provided.
2
 3
 6
 7

8
 9
 10
 16

18
 19
 20
 21

22
 24
 30
 31

32
 33
 34
 35

36
 37
 40
 41

42
 44
 46
 54

1
 2
 3
 8

10
 12
 16
 20

27

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