Let's head out to the workshop bench to do some drilling then to the kitchen sink to remove the paper drilling guides. Do you remember that the glue underneath the guides was washable? 

The drilling is fairly simple since the enclosure is a soft ABS plastic. Drill bits have a tendency to drift away from center of the hole in soft materials like ABS unless you use a drill press. Since we'll be using a hand-held power drill for this build, we'll solve the drifting issue by drilling two successive sizes of pilot holes.

Small pilot holes are the best way to accurately guide larger drill bits. Be patient -- the components will fit better if the holes are drilled with precision. Take it slow and easy. Carefully center the drill bit before spinning the drill. Use light pressure at a slow speed and let the drill bit do the work.

Because the final diameter of many of the 27 holes is 1/8 inch, only eight larger holes remain to be drilled at this point. Let's start with the two largest holes, 1-7/8 inch. These are for the carbon filter in front panel and the fan in the rear panel.

Clamp the enclosure to your work surface to stabilize it when using the larger drill bits and hole saw. Two clamps placed as shown should do the job.

A sharp hole saw will do most of the work for you. Your primary job is to apply a light, even pressure and to keep the hole saw level while drilling. 

The final eight holes will require a special drill bit that can cut a variety of hole sizes. The step drill bit shown below can create hole sizes from 3/16 to 7/8 inch, perfect for our remaining 1/4, 3/8, 9/16, and 7/8 inch holes.

Operate the step drill bit at a slow speed using light pressure. Hold the power drill level while drilling. The step drill bit should create some nice spirals of cut plastic if you're doing it correctly.

At this point in the process, you will only be able to remove burrs from the enclosure's exterior. Keep the countersink and small file handy for later. You'll have the opportunity to clean up the interior after the guides and front panel are removed.

After creating a nice mess in the workshop, it's time to head to the kitchen sink and remove the drilling guides.

Here's a glamour shot of the enclosure after drilling. We'll need room to fiddle with the wiring, so the acrylic rods and the prismatic plastic window will be attached later.

Now on to the electronics part of the project!