For this Instructable, I'll be using an old WD Caviar hard drive. Drive designs differ, and some are better for this project than others.
You will need:
Torx-6 and Torx-8 screwdrivers
Phillips head screwdriver
Drill and bits
3/4" clock movement
Once you've gotten all the screws, you can cut through the tape around the edge and open it up.
Step 2: Disassembly
Then, remove the single screw keeping the actuator retainer in place. Work the retainer up and out. The arm should swing freely now.
Next, unscrew the motor assembly and pop it out.
Step 4: Pre-modification
It's also a good time to spray paint your hands, if you don't want them the stock color. I went with black.
Step 5: Modification
Place your motor assembly upside-down in a vice (preferably padded) with the spinning part hanging freely. Place an old screwdriver or something of the sort in the center and tap it with the hammer. Eventually, the whole spin assembly will fall out. Sometimes this step takes two taps, sometimes it takes ten minutes. Be patient.
Once you've picked up your motor, place it back on the vice, this time right side up. Repeat the previous step, and the spindle will pop out, along with some bearings. Make sure to get all the bearings out. If the top piece (edged by some blue adhesive) stays in, don't worry about it.
Step 6: Modification
Reattach the motor base to the body, and use the hole as a guide to drill straight through the circuit board on the back.
Switch bits for a moment and use as 13/64" bit to drill two holes on your marks in the cover.
Step 7: Reassembly
Reassemble the platters and spacers on the mount, and screw them back in.
Place your reassembled platter assembly back where it belongs, and move the actuator heads back into place.
Affix a 3/4" clock movement (I use Walnut Hollow) through the hole in the drive, and tighten the nut.