The A3000D does not have room for an CD/DVD drive. You could install a slim laptop drive but that would be modifying the front of the Amiga, no way.
I have a Proxmia Power Director, it has a space for the old 5.25: floppy disks, remember them. I took the Proxmia apart and modified it to allow the installing of a CD/DVD drive.
At first, I had an IDE cable and power from the Amiga going to the drive. Then I used an IDE to SATA adapter. See my posts on eSATA project.
Here are the pictures on how I did it. Please if you can improve on this, do it. I do plan to make it look better, I got it, an Amiga Ball sticker from eBay right over Proxmia. There is NO wiring modification.