Materials:

• PVC pipe, naturally
• PVC cross connector that snugly fits around the diameter of the core pipe
• Steel/iron rod of diameter to fit inside the core pipe (1/4" welding rod works nicely)
• Padding (pipe insulation- brown stuff is best, black compresses too fast)
• One penny
• Duct tape and electrical tape
• Round file, fairly small diameter (1/4" to 1/8" tapered works great)
• Other necessary tools for manipulating the above materials
• Personal fixins- leather/wire hilt wrap, pommel attachment, decorations

First, cut the core pipe to length- one piece of pipe, unbroken from pommel to blade tip.  Decide where you want the crosspiece to sit; the cross connector will, naturally, hold the crosspieces.  Hold the cross connector against the core pipe, and mark the top and bottom against the pipe.  (Don't score the pipe, scoring will weaken it; use pencil, or a wrap of electrical tape at the blade end of the connector.  I wrap enough electrical- 10, 15 layers on top of each other in one spot- to actually create a solid "barrier" against which the connector will later sit.)

Use the round file to file out the inside of the cross connector in one direction.  The connector has ridges inside meant to stop the pipe from going in deep; you need to get rid of those completely.  It takes awhile and is a messy job, but it's well worth the effort.  A good indicator- the inside of the connector is polished; when you're done filing, there should be no shiny spots left inside along the path you filed.  Work on it to the point where the connector can slide over the core pipe, not necessarily easily, but not so tight that it takes excessive effort to slide it down.  (They're a PAIN to get off if you hit a sticky spot and can't keep going forward.  And excessive strain on the cross connector will break it.)  Once the filing is complete, slide the crosspiece over the hilt and up against the electrical tape wrap.  Bind it in place by adding a similar wrap on the pommel side.

With the cross connector in place, you can now do a number of things in any order, it doesn't really matter.  The sword will turn out slightly different depending on which order the steps come.

Weighting the sword: cut a piece of metal rod to a length from the end of the pommel to the hilt side of the crosspiece.  Wrap the rod with electrical tape in 3 places, such that the electrical tape diameter is slightly larger than the inside diameter of the core pipe.  Use a hammer to pound the weighting rod down into the pipe from the pommel end.  (The electrical tape will go through a number of contortions, creating sticky surfaces on the inside of the pipe.  That plus sheer friction will hold the rod in place.  You may have to cut off excess electrical tape that goops out the end of the pipe.)  Test the stability of the rod by copious shaking, and then by dropping the remaining metal rod down the inside of the blade to strike the weighting rod from the top, see how far (and if) it moves.  If the friction is too loose, use the remaining metal rod as a striker to remove the weighting rod the way you put it in, and try again.  This may take several tries to get it satisfactorily anchored.

(I used to drill through one side of the core pipe and insert a wooden peg to hold the weight in place.  Think of what that does to the weapon's lifespan :)  This is a reasonably easy alternate solution.)

Crosspieces: cut small lengths of PVC and insert them into the cross connector on either side.  Presumably there's plenty of opportunity for creative design here, but I never bother, I like the simple design.  Additionally, for strength, I've lately taken to the practice of replicating the weighting operation inside the crosspieces.  Inserting a metal rod into the crosspieces ensures that it will take a VERY solid blow to dislodge the PVC or break the cross connector.  That's not to say it becomes immune to damage, they actually break fairly often.  BUT, with the rod in place, even if something breaks, I find a little electrical tape will often fix the broken joint to the point of a small wobble.  Also note that, by weighting the crosspieces, which are almost invariably behind the balance point of the weapon, the overall weapon balance improves slightly.

Padding: first, use tape to affix a penny flat across the blade end of the core pipe.  This provides a sturdy, flat surface at the end of the pipe, rather than an open ring; more surface area means your stabbing tips will last longer and be less likely to punch through the padding.  Attach the padding by whatever means you see fit and add an appropriate stabbing tip.  You may notice that the padding slips nicely over the electrical tape wrap at the top of the cross connector; with a little effort you can shove the padding down over the connector itself.  Just depends on what look you want.

To create a blade with edges and flats, some people will cut an extra length of padding in half along the circular diameter, and affix these U-shaped padding pieces to either side of the core padding.  This is a cosmetic and functional change, and entirely up to the builder.  Be warned that it will significantly alter the inherent balance of the weapon.  For the longest time I scoffed at this idea; my martial arts training left me with a very clear concept of the flat and edge of a blade, and I never felt I had problems striking edge-on.  Personal preference, obviously.

One more padding consideration- I like to tape the blade such that I have a "foundation" of padding that basically never gets hit, against the cross connector.  When my padding wears out, I cut it off a few inches above the foundation (being careful not to score the pipe), and slide the new padding down to that point.  The end result shows a seam where the old padding and the new collide, but it's a small price to pay for the convenience of being able to maintain the sword easily.

One more note on balance.  By cutting a metal length from pommel to crosspiece, you maximize the hilt weight.  But if your hilt is too long for the blade, or your metal is extremely dense, I suppose it's possible that the balance point might shift *behind* the crosspiece.  Perfect balance is considered to be a center of gravity under the blade, somewhere within an inch or two of the crosspiece; this is the point at which the sword loses most of its inertia and becomes extremely easy to control.  (It also loses momentum as a result- there is a tradeoff.)  A hilt-heavy weapon would actually resist being moved toward the opponent- something I'd like to feel and experience sometime, but never to fight with :)

Anyway, the short of the above paragraph: if you overbalance your sword such that the center of gravity sits under the hilt, cut the metal down a bit.  Start long and assume you need the full length, though.

Stabbing tips (because I'm on a roll :).  I cut the padding such that it extends between a half inch to an inch beyond the tip of the weapon; then I cut a small circle of padding, cut an arc out of that, and coil it so it fits neatly inside the cylinder at the top of the weapon.  Then, I cut a piece or two of padding out of the side of the tube, giving me a flat surface, and trim that so they stack on top of the tip, covering the entire surface of the sword tip.  Tape it all down, and it becomes a fairly squishy, yet sturdy tip.

I experimented with using PVC glue to adhere the cross connector to the core pipe, and then the crosspieces within the cross connector.  After some experience with the way those swords broke, I've come to the conclusion that gluing sword PVC is a Bad Idea (TM).  Breakage always seemed to happen along a line along the edge of the glue joint.  I can only conclude that the rumor is true, the glue weakens the PVC and caused it to break at that point.  Since banishing the PVC glue, my swords tend to last a bit longer.  By no means is this a horribly sturdy design, however.  I've made every modification I can to extend the lifespan, but they do break.

One note- if the core pipe breaks inside the cross connector (which has happened to me), the sword may creak and wobble a bit, but there seems to be no tremendous ill effect....

When the thing breaks down completely, you may be forced to take a saw, hammer, or other implement of mass destruction to the hilt in order to get the metal bar out.  Effort well spent, IMHO, so long as the weighting rod doesn't come flying out in either direction.