The Selection Machine is one of Dr. Eggman's machines in Sonic X. Eggman uses it to help him select one of his robots when he needs them.
The Selection Machine's function is to randomly select one of Eggman's robots whenever he needed one to help him with his plans to conquering the world or at least defeat Sonic the Hedgehog and his friends. It highly resembles a slot machine and is built into his base.
In "Little Chao Lost," it was seen as a stand-alone machine carried by Decoe until the doctor ordered him to unpack his knapsack. He used it to pick out E-66 Da-Dai-Oh during his vacation to attack those who were camping with Tails.