You even get a small score pad to track the number of strokes. This game allows you to design your own course, and it doesn't need a green. Make the competition easy to encourage all players - the winner can be the player with the best of 5 or 10 shots, or any other combination you'd like to try. Ask a qualifying question to play - either for fun, or having to do with the library. If you really get fancy, you can design a Par 3 course with holes strategically placed throughout the library.
Toy stores offer a wide variety of bowling gear.
Action Bowling Game by Tudor Games. Bowling Set in a Pouch by Battat. Called the ideal bowling set for beginning bowlers. There are ten red, blue, and yellow pins, and two balls. This set even comes with a vinyl carrying case.