For the containment of any wild creature a suitable cage or habitat is necessary. Millipedes are undemanding in this sense, and it is generally recommended that enclosures be 2-3 times the length and width of the longest specimen that will be inhabiting it. Depth of the enclosure should allow, in general, for the substrate to be as deep as the longest specimen, though this rule isn't hard-and-fast, and exceptionally large specimens can do well on substrate half their body length. For species that tend to enjoy climbing, making sure the enclosure has the space to incorporate some upright branches or larger logs is recommended. If a high density of specimens is going to be maintained, or breeding is wish to be done, it is recommended to increase the enclosure size two to three times depending on the fecundity of the species in question. This allows for a greater amount of food to be present in the enclosure and thus prevents die-off amongst early instar millipedes that might otherwise occur in a cramped enclosure that quickly becomes food-poor.
Plastic, glass, and acrylic enclosures all work equally well depending on one's needs; all habitats need to be water-proof and capable of maintaining moist soil, and as such Kritter Keepers, screen cages, and other such habitats with very levels of ventilation are not recommended. Common millipede cages include ten gallon (38 liters) aquariums, custom-made acrylic cages, and Sterilite bins. Secure lids are also a necessity, as many young millipedes are adept escape artists if given access to a lid, while larger specimens are very strong, and have been known to pop the lids off of snap-tight deli cups.