Any kind of cage with a solid bottom (not wire!) is okay.  As for
     size, a rule of thumb is a _minimum_ of two square feet per
     guinea pig.  If they are not allowed to run around the room for
     exercise on a more or less daily basis, they will need a lot more
     space to be happy and healthy.  See next section for what to use
     for bedding.  Bedding should be a couple inches thick, and should
     be changed when it looks soiled, usually once or twice a week.

     Since guinea pigs do not jump very high, you do not need very
     tall sides for whatever housing you provide.  This allows you to
     be creative, and you can design a wonderful housing and play area
     for your companions.  For a very easy basic kind of area, that
     you could add to later, you can use 4 - 2"x12" boards, nail them
     together at the corners and sit the resulting "frame" on a piece
     of linoleum remnant.  And remember, the bigger the better.  The
     litter/bedding can be placed directly on the linoleum.  When it's
     time to clean the whole area, just pick up the "frame", sweep up
     the litter, and mop with vinegar.  If that's the extent of your
     woodworking abilities, instead of building a small wood house
     without a floor (they like to have a dark place to hide), you can
     put a small litterbox, filled with bedding, inside a grocery bag.
     Guinea pigs are perfectly happy using that as a place to sleep
     and hide.  (Although expect them to destroy the grocery bag
     within a week or so.)  Or you can use a medium-sized cardboard
     box, cut out one side for a door, and line the bottom with
     litter.

     Another option is to allow the guinea pig free run of one or more
     rooms.  Since guinea pigs instinctively will mostly confine their
     bathroom activities to safe "homes", you only need to put
     litterboxes where they are fed and given water (again, cardboard
     boxes work fine, although prepare to replace them every few
     months; I use an opened cage for the pellets, alfalfa, and water,
     and give fresh veggies in a cardboard box), and lay down
     cardboard in some of the darker corners.  It also helps to block
     off couches and beds.  Again, since guinea pigs don't jump or
     climb, it is only necessary to see that all wires and chewables
     are a foot or so off the ground.  Remember to watch where you
     step!  Guinea pigs are prone to following feet around, especially
     if the associated person is known to hand out vegetables.

     If you decide to go with a store-bought cage, I recommend the
     sort with a plastic tub on the bottom and a removable cage part
     on the top, because it's convenient and easy to clean, but any
     kind without wire flooring is okay.  Wire flooring damages guinea
     pig feet, and if it is too widely spaced they will often break
     their legs in it.  Try to avoid cages with wood on the bottom
     too, since urine will soak in and be impossible to remove.  It's
     helpful to line the cage with newspaper before putting in
     bedding.  You can use a cardboard box with the bottom side cut
     out (so that urine soaks into the bedding instead of pooling in
     the bottom of the box) for a hiding place.  Remember that you
     need to make sure you have several square feet per guinea pig.

     You will need to buy food and water dispensers.  For water, most
     people recommend one of those rodent bottles (available in pet
     stores) with a stainless steel tube coming down to drink from
     with a stainless steel ball at the end of it.  Don't give water
     in a bowl (as one might do with a dog or cat) because it will get
     soiled.  For the pellets and the hay, you can experiment with
     what works for your guinea pig.  I've had some success with food
     dishes designed for parakeets, but your mileage may vary.  Other
     accessories are optional.  Some report that their guinea pigs
     enjoy parakeet toys, such as the mirrors with the bells in front.
     They also like to climb up very gentle slopes; make a climbing
     area out of bricks (this will also help keep the toenails short),
     or give them a pile of (clean) discarded clothing or an old
     sheet, as space allows.  As long as they are given pellets, a
     salt wheel is not necessary, but it can't hurt, and lasts nearly
     forever.