Derp, if it were blind-tapped you wouldn't need a backplate because there would be no holes on the other side of the tray, derp.
Which is why I am asking, if they are truly blind-tapped, why does it need a backplate to slide into like that? Why not just leave it bare on the backside and have a 1-piece tray. My guess is because it's not truly blind-tapped, but through-tapped and has a backplate covering it. If it's mounted with blind taps to the backplate and the 1/4 tray isn't blind-tapped for the mobo tray holes, that would make sense. If the 1/4 tray is blind-tapped for the mobo holes, why have a backplate covering that up? Show it off that you have stuff mounted to one side and no holes in the other side.
Blind-tapping involves drilling a hole usually around 1/16 deeper than needed for the tap and tapping the required depth, never breaking through the backside of the material. It takes a lot of time and precision and special tools to do this.
I'm also curious what the screws are holding against for the reservoir holder. I would imagine an entire channel cut out the width of the screw head (or bolt or whatever it mounts to on the other side) and then a through cut the width of the screw threading. Again, you would need the backplate to cover up holes in the tray.
Derp, look at the photo more closely. The mobo tray is solid. There is a large section machined out of the mobo tray and replaced with another piece for the res mount. I'm assuming the slot you see for the res mount is a dovetail dado or something similar. I would have done it differently but they chose to do it the way they did. So there is no "back plate" DerpEdited by aeRsneM - 9/6/12 at 7:09pm