Installing MacBook Pro 15" Unibody Mid 2010 Dual Hard Drive - iFixit Repair Guide
Amazon.com: Odyson - Optical Drive SATA Flex Cable Replacement for MacBook Pro 15" Unibody A1286 (2009, 2010, 2011, 2012) : Electronics
Install a 2nd HDD/SSD by replacing the optical drive - Upgrade your old Macbook pro - 9to5Mac
Amazon.com: SZYIKUER 2nd 2.5''HDD SSD Hard Drive Caddy Tray Replacement for MacBook Pro 13/15/17 inch A1278 A1286 A1297 2008 2009 2010 2011 2012 Internal Laptop CD/DVD-ROM Optical SuperDrive Adapter : Electronics
Replace your 2009-2012 MacBook Pro HD with an SSD
Amazon.com: 2nd 2.5'' SATA HDD SSD Hard Drive Disk DVD CD ROM Optical SuperDrive Caddy Tray Adapter for Apple Unibody MacBook/MacBook Pro 13 15 17 Early mid Late 2008 2009 2010 2011 2012.etc : Electronics