It's a laptop CD drive like this one:

I am planning on building a custom case, and I want the drive to be totally hidden. So part of the case itself will be cut out and attached to the front of the drive, and will move with the tray. Of course this means the button will be covered up, which is why I want to relocate it.
The drive itself isn't necessarily "perfect", it's just one which I happen to have. If an alternative slim tray-loading CD drive with the button not located on the edge of the tray were available at a reasonable price, then that would make things easier (assuming the contacts for the buttons are fairly easy to solder on to).
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moto