Print out the measurements table.

Cut your elements to length, adding 1 mm, starting with the longest ones.  As I don't own a band saw, I found my scroll saw worked well for this.

Sand each until it hits the target length, squaring up the ends.  If you over-shoot, cut it down to be the next smaller element.  You need to be accurate to within 1 mm for good performance.

Cut your 3/4 in tube to length.  Square up the ends as you'll be making a lot of precise measurements from one end.

Mark a straight line along it's length.  Rotate the tube 90 degrees and mark another line along it's length.

Easiest way I've found to get an actual straight line is to put the tube into a similarly sized bit of angle iron and then scribe along the top edge of the angle.

Using the 'Boom Position' numbers from the table, mark your reflector, dipole, and director positions along the line you made. Label them.  Rotate your tube 90 degrees and mark again on your second line.

Using a 1/4 in brad point drill bit in your drill press, drill through the reflector holes.  These are the ones closest to the end.  Make sure you get this one perfect as it will control the rest.

Technically brad point drill bits are for wood, but they produce very clean cuts, essentially square bottom holes, and self-center without a pilot hole in aluminum.  I get a couple hundred holes out of each one.

Insert your reflector element into the reflector holes, tape it into place so it doesn't slide out, and then tape a small level to it.  The level will allow you to control the rotation of the tube as you drill along it's length.

Drill the remaining element positions. Start the drill at each position, back off on pressure, and sight down the tube to the level. Rotate the tube until the level reads 'level', then clamp/hold it tightly and drill through the top. When you break through the top, check your level again, and continue through the bottom. The brad point drill bit also does not wander like a standard high speed steel bit does upon contacting the inner wall of the tubing so you can reliably drill straight through.

Keep the level you attached to the reflector element 'level' and all of your holes will be perfectly parallel. This is one of the only ways I've found to accomplish this with any reasonable amount of repeat-ability without building a jig. It is important that your holes are all perfectly parallel and you need to be accurate in your positioning to within 1 mm for best performance. Take your time now and you'll save a ton later as you won't have to bend each element into line.

Mark each element from both ends, to the 'insert to' depth.

Line them all up so they go smallest to largest.

Start with the largest, put it in the first director hole, and center it in the tubing.

Lay it flat, so the director is now horizontal, check your marks again, and drill through the top of the 3/4in tubing, and through the director. You are removing more than half of the director thickness, so go slow.

Leave the director in place. It will stay put now as the flashing from breaking through with the 1/8th in drill bit will keep it in there.

Repeat for the rest of the directors.

Change back to your brad point drill bit. You are going back over the 1/8th in holes you just made to countersink the rivets.

Drill the first hole, until the top of the rivet will be flush. You'll remove about half the thickness of the 3/4in tube to do this.

Set your depth. Drill the rest to match.