The Mini Chainsaw, a devastatingly effective weapon rewarded for finishing the "Out of Control" scoop mission, is the smaller counter-part to the chainsaw. The weapons' durability can be expanded by three different books. The Mini Chainsaw can easily dispatch Psychopaths, and even though Adam the Clown is one of the hardest bosses to beat it's highly advisable that you obtain this weapon and all 3 skill books. Unlike the regular Chainsaw, Frank can carry these in his inventory, making them even more useful.
After defeating Adam the Clown, the Mini Chainsaw will respawn at the Space Ride in Wonderland Plaza. There is no limit to how many you can carry in your inventory.
Books
With books from around the Mall, you can make the Mini Chainsaw more durable. The Criminal Biography book from Wonderland Plaza, and Engineering and Entertainment book from Paradise Plaza each triple the life span of the chainsaw: with all three books the Mini Chainsaw can go from withstanding 80 kills to 2160.