In addition to the balloon people I discussed the other day, the Oz books also have other characters and societies made out of rubber. One such creature is Para Bruin, the Rubber Bear, who makes his first appearance in
John Dough and the Cherub. He's capable of stretching and bouncing, and he joined John in his flight from the Isle of Mifkets to Hiland and Loland. When the gingerbread man was crowned king of these two countries, Para became his Chief Counselor. He puts in an appearance in
The Road to Oz, accompanying his monarch to the Emerald City and performing a demonstration of his bouncing for Ozma and her guests. Another notable rubber character is the Bell-Snickle, but
I've already covered him.

In
Tik-Tok, the party of adventurers journeys through the Rubber Country, a part of Ev where the ground, rocks, and trees are made entirely of rubber. A brook runs through this country, but its water somehow doesn't get things wet. There don't appear to be any inhabitants of this dull gray territory, which is right above the Nome Kingdom. In fact, Ruggedo and Kaliko try to delay the travelers using magnetic rubber wires, but learning they can safely walk through the brook allows them to thwart the Nomes' mischief.
Purple Prince contains a brief visit to the rubber city of Squee Gee Ville, which is apparently located quite close to the Emerald City, yet there's no sign of any communication between the two towns. That seems to be the way of the reclusive communities in Oz, though. The people, known as Squee Gees, are based on old rubber dolls that would talk when you squeezed them. This means that they have to squeeze or punch each other in order to hold a conversation, making a discussion look rather like a battle. Randy and Kabumpo leave the rubber city without even spending an entire chapter there, bouncing out on the springy rubber of which the ground is made, which is kind of weird as elephants can't jump. Yeah, I know they can't talk either, but suspension of disbelief is easier when fantasy characters are portrayed realistically in most ways. Oh, well. Anyway, the Squee Gee encounter is brief and uneventful, but it did introduce the phrase "exsqueeze me" decades before
Wayne's World.
Finally, while Dorothy and Percy are chasing after Singra in
Wicked Witch, they come across a rubber band. If you've been paying attention to how many puns there are in the series, you wouldn't be at all surprised to find that they're people made of rubber who play instruments. They play a few songs for the pursuers, but there isn't a whole lot more to say about them.