Hi You can find Solidworks models, step and iges files of all kinds of Pneumatic grippers and Robotic grippers at www.agi-automation.com/pneumatic-grippers.htm
You can use a pneumatic o-ring installer that can be bench mounted or used in an automated assembly machine. The unit will spread the oring and eject into the grove. The company is AGI and the part is AGP-6 OR under grippers. The web site is www.agi-automation.com