Guinea Pig Cages
As a general rule any guinea pig cage should be at least 8 square feet for one guinea pig and 2-3 extra square feet for each additional guinea pig.
There are a number of guinea pig cages available from pet stores with a plastic base and a ventilated plastic top or plastic base with a rigid wire top intended for guinea pigs to be kept indoors. Unfortunately the majority of these types of guinea pig cages are too small for a guinea pig to live in permanently and so are more suited for housing a guinea pig for short spells only or for travelling with a guinea pig. Many of these cages do not provide the guinea pig with a sheltered area in which to seek privacy although some kind of sleeping box can be placed inside the cage to provide this.
Plastic based cages do have the advantage of being lightweight, easily cleanable and not soaking up urine as wood does.
There are a variety of metal guinea pig cages available from pet stores with a metal base and a rigid wire top intended for guinea pigs to be kept indoors. As with the plastic cages many of these types of guinea pig cages are too small a guinea pig to be kept inside for any amount of time and will require the addition of a sleeping box to give the guinea pig an area where it can feel protected and secure in which to rest and sleep.
Metal cages tend to be cold and so deep floor covering is needed. Cages with wire mesh floors should be avoided as these can cause sores on the guinea pig's feet.