Is the MBP unibody optical bay drive adapter compatible?

Thanks, I guess I should have been more specific. I already have installed a second drive in my MacBook Pro. I was hoping that optical bay adapter could be dropped wholesale into the Mac Mini I have, even though they are slightly different (the MBP optical bay adapter only takes 9.5 mm drives).

Does anyone know if that's doable?

You don't need the optical drive frame in the mini. Review the guide I linked above. You still need some sundry parts and a cable to attach the drive to the systems drive frame. Thats what the dual drive kit offers the tools and the loose parts. If you have the needed tools all you need is the rubber bushings, screws and SATA cable.

OK, but the guide above is for the 2011 - 2012 unibody Mac Minis, not the 2010 Mac Mini that has the optical drive (which is the version I have). That's the main reason I'm asking whether the MBP unibody optical bay HDD caddy would work - my Mac Mini has an optical drive and my MBP's graphics card died, so the path of least resistance would be to drop the MBP optical bay HDD caddy into the Mac Mini if it works...

Plus I can't really tell if the hard drive trays are identical in the 2010 vs. 2011/2012 Mac Minis from the photos.

OK, we got our wires crossed here. You in fact have a '10 model not '11. I've corrected the model info for you and here is the correct guide: Mac mini dual drive guide. Here is the part you will need: 12.7 mm SATA Optical Bay SATA Hard Drive Enclosure. This is a special unit for the mini's with optical drives.