HP 2.5" HDD/SSD 2-in-1 Optical Bay Bracket K4T74AA B&H Photo
Best of both worlds: putting an SSD in your optical bay « Super User Blog
2.5" SSD to 3.5" SATA Bay Adapter by secv | Download free STL model | Printables.com
ORICO External Hard Drive Enclosure Dual Bay M.2 SATA SSD Enclosure RAID USB3.1 Gen2 Type C 10Gbps B-Key/B+M Key Solid State Drive Case Adapter for SSD Size 2230/2242/2260/2280 Support UASP - Walmart.com
SSD/HDD Rack, 2-Bay 3.5 Bay to 2.5' SATA - Drive Mounting Brackets & Accessories | StarTech.com Denmark
SSD Mounting Bracket for Quad 2.5" SSD in Cerberus or Cerberus X - DENSITY.sk