Using a lamp tube as a base, I am going to explain the way I do this, and the tools I used. For those using plumbing tubes, and also for people who don't have alot of tools and mainly use a Dremel, I'll give alternate methods wherever possible! 

I'm also not convinced that there is an extra allen bolt under the door catch so I only do six. Accurate or not (shoot me if I'm wrong)that's just my personal preference. Sorry I don't have prices, but all of these parts are really cheap, between 50 cents and $2.00 average.

Parts list:
  1) 6 flat head,taper allen bolts. 1/4-20 x 1/2"
  2) 6 nylon nuts (Lowes or Home Depot)
  3) Two 1-1/4" PVC insert couplings (Lowes)
  4) Bolt hole placement (missing sorry   -ed)

The tools I use are as follows:
   1) Variable speed Drill w/drill press mount.
   2) Pine V Block
   3) Step bit
   4) 45 degree countersink bit
   5) curved sufrace/ small rat tail file
   6) oil

I've found that a drill press and V Block combination works the best. I got my V Block from BobaDebt. I can't say if he'd make any more, you'll have to ask him. He also inspired me to get a drill press, after seeing his amazing work. The step bit takes the place of many bits. I had to get one since my drill wouldn't take a 1/2" bit, plus you don't have to keep changing bits when you drill large holes!  You can do this without using the countersink bit, but you'll have to do a bit of epoxying to make up for it.

Insert the "insert" into the tube.

If you're using the lamp as a base, you'll have to POUND this in, and once you do, it'll NEVER come out!!!!  The best way to do this is to place your tube on a flat scrap of wood(so you don't dent it) and pound the insert in with another one making sure not to pound the second one in so far as you can't get it out. I made this mistake, and had to drill a hole into the second one, string some wire through it,and tie it to a fence so I could yank it out!

If you're using plumbing tube, it fits really loose so don't worry about it, I'll come back to you guys and explain the alternate method!

Once the insert is in place, Drill a 7/16" hole into the outer tube. Withe the step bit, This was the 5th step up. The 6th step will make a 1'2" hole. The friction causes the PVC to melt and flare downwards into the tube and creates a deeper hole. I used a low speed for this and ALWAYS use plenty of oil around the bit (stopping after each step-up to apply more) to keep it from getting dull. The flaring can be either cut off, or pushed back up into the hole to support the bolt.

 * If you aren't going to use the countersink bit, drill your holes 1/2" and push the flaring up into the hole.
 

Next, fill the hole with epoxy and insert your allen bolt.  The pushed in flaring should hold the bolt in place while the epoxy dries. When I tried this method, the epoxy was enough to hold it in the tube, but if it pops out, you might have to also add the nylon nut from the inside, and epoxy the nut to the insert before tightening it down.
 

Using the countersink bit, carefully bevel the front and back edge of the hole untill the bit starts to hit either side of the hole. Since the hole is on a curve, you'll never bevel the whole hole (Man I'm corny, I gotta stop) just the front and back edges. As Padawan Connoli pointed out earlier, the Real props bolts aren't perfectly flush. You'd have to have curved heads on the bolts to do that! Test fit the allen bolt . I've found that I had to barely bevel the sides of the hole and the bolt fits perfect. If you bevel it to much, you'll end up with too much of an oval shape and the bevel will show on the front and back of the hole.  Go with a slow speed, use plenty of oil and stop to check the fit often and you can't go wrong. Patience is the key when drilling and tapering, remember...you have to do at least 6 of these!

Basically, you're going to end up with a hole that has 1/2" wide tapered ends (running the length of the tube, and 7'16" sides. The tapered head of the bolt will meet the 7/16" sides and you shouldn't have any gaps.
If your bit happens to chatter while tapering ( Mine does) and the taper is jagged, use a curved rattail file to smooth it out.

The hardest part of this comes when you try to fit the 3 bolts that are just forward of the midband side by side. It gets pretty tight inside the tube with the nuts and threads poking through. I used nylon because you'll find that you won't be able to fit all 3 together. The best thing I could come up with was to screw in the 2 side bolts of the trio, and simply drill stright down into the middle hole(through the nylon nuts) and then thread the third bolt in between the two nuts. Here are a couple of pictures of the final assembly...

For those of you using plumbing tubes as a base, the directions are a little different.

First off, go ahead and drill your holes inthe main tube without the insert! It's your choice if you want to drill the holes 7/16" and taper, or 1/2" and epoxy. Since it's fits loose, place it inside the main tube, and mark the centers of all of the holes you just drilled.

Take it out again, and drill 1/4" holes.  Next, taper these holes with the countersink bit.  Reinsert the PVC insert and line it's holes up with the holes in the main tube. You may want to wrap the tube in tape before you put it back in so it fits snug.  Insert the allen bolts and you're all set! 

If I could do it like this with the lamps I would, but the connectors won't come out of the tube once it's inserted so that's the difference.

Here's a cross section to show you why the connector is necessary:

Here's what you need to do with the inserts.  Cut one of the two like I've shown in the diagram below.  You want to make sure you cut the insert in half just behind the raised middle ring. Next, cut 2 rings off of the piece with the middle ring on it.

The other half of the insert( piece without the middle ring) gets inserted into the tube first. Then insert the second complete insert. The half with the middle ring gets inserted last and you want to wait until you have drilled your recharge socket holes to put this in.  I modified some pins I found inside a disposable camera for the recharge pins, and tapped them into the last insert piece. Only one of the pins is visible when the shroud gets put on so you can leave the other pin out. The last insert piece also serves as a shelf to epoxy the circular emitter plate.  Here's a cross section of what I'm talking about: