*******DO NOT USE ELASTIC BANDS!!!!!!!!!!!!!11111!!!1!11!*******
Just opened my case to clean the fan filters and all three of my HDDs are hanging down by the SATA cables just resting on top of each other... if it wasn't for the SATA power cables being a bit shorter on each drive, the board on the underside of each drive would've been resting on the top of the one below it causing who-knows-what catastrophic disaster in there!!!!
So either stick with bungee cord, or just use the HDD rack as intended and find some other way to make it shush!
/warning