Hiding places are a necessity - an overturned plastic tub or pail, or a cardboard box is the least you could do. (the cardboard boxes can just be discarded if soiled and replaced they are perfect barricades for floor time).
Large diameter PVC pipes (with thick walls) make good tunnels and hides as well but make sure your cavy won't get stuck.
I've noticed that if a hidey doesn't have multiple entrances so sometimes I cut holes in the sides and sew them back together myself. Just crafts.
Takes these strawberries for example, after I cut holes in the sides they became the favorite of all houses in quite some time.
