The most common thing for these little fuzzy dudes is a home/cage. So-- you may be thinking that "OH- WELL I WILL JUST GO GET A CAGE AT THE PET STORE". No-- ok? Pet store cages are bad clearly most of em. The size is very bad they need allot of space to run/excersize.  These are cages l recommend:

These have the right size for them! So l recommend getting one of these for your guinea pig.
But--
You may be wondering--
"Can l make one?"
Of course you can! You can make a C&C cage! Those are very good: here are examples of c&c cages:

These are very good c&c cages!  You can use these pictures as a reference.
You can make your own with wood too! Just make it big enough^^.