Mark the spot

   Bring the spacer as close to the hole as possible and use a pencil or marker to mark a spot where you will be drilling.

Drill it

   I used my Dremel with the supplied drill bit and hacked away a hole at the bottom end of the spacer.  This will be done to two spacers.

Perfectly sized

   The bit makes a hole that fits exactly to the size of the hole on the hard drive.  Do this to the other spacer:

Both done

   Flip the spacers around to the other end and measure two spots so you can make the other holes:

The other end

   Take the Dremel and drill the same hole on the other end.  To make it easier with less slipping, you may want to drive a pilot hole through the metal. These spacers are quite smooth.