Buy a cheap bar of wax or soap. Use a knife to carve out the shape you want for the new drive. Next buy some loctite quick set epoxy. This is important. It needs to be quick set , 5 minute or less epoxy. Epoxy generates heat when it cures and those temps can be pretty high so you want to keep it as short as possible to keep from damaging the drives.
Put some epoxy in the bottom of your carved out bar. Place the drive inside making sure not to epoxy over the usb connector. Fill the epoxy almost to the top of the mold covering the drive.
After about 10 minutes it will be better than it was. The wax/soap can easily be removed if any sticks.