There are a lot of tutorials online about making PVC weapons, and a lot of good ones at that. The problem I've had with most of them is that you end up with more of a club than a blade shape when you're done, or they use fancy (i.e. expensive or hard to aquire) cores and foam. So I'm recording what I've found to be the best of both worlds. I'm not claiming that this idea is unique, or even that i'm the first person to make a PVC weapon this way. But I haven't found anything online that indicates they wrote about it if they did. If you've seen/done something else like this, please let me know about it in the comments.
Step 1: Tools and Materials
1 piece of 3/4" schedule 80 PVC conduit, equal to the finished length of your weapon, minus about 2 inches for stabbing tip. (You can find it at electrical supply stores. You don't want the schedule 40 stuff they sell at Lowe's and Home Depot because the dowels won't fit right, and because it's weaker.
3/4" oak dowel(s) the same length as your PVC. I've only found them in 3' lengths, which seems to be no problem. Just use more than 1.
1" schedule 40 (repeat, forty) PVC conduit for your crossguard.
1 3/4" PVC end cap for a pommel. (That's just what I use, you may want to make your pommel out of foam so you can bash people with it. I don't, and I don't think it's a very good idea.)
1" pre-slit polyethylene foam pipe insulation. It's sold in 6-foot lengths. a rule of thumb for how many to buy is 1 for every 18 inches of blade.
Double-sided duct tape.
Regular (single-sided) duct tape.
Boiled linseed oil.
A drill, and a 1" hole saw. It's that little white thing in the picture, and you need it to make your crossguard.
A box-cutter/utility knife. Make sure it's the kind with the break-off blades, so you can extend it all the way. You're gonna want a fresh blade for it.
Leather work gloves.
You'll also need some way to heat your PVC. Some people pour boiling water over it, some people use a blowtorch, and some use purpose-built heat guns, which are basically a hair dryer on steroids. I use a torch. (A word of warning: If you use a torch, do your best not to singe the PVC, because those fumes are toxic. Keep your torch well back from your PVC, and wear breathing protection. And DO IT OUTSIDE. That goes for the PVC cement too. Remember, manufacturers' warnings are there for a reason. Always read and follow them.
Step 2: Making Your Core.
Take your oak dowels, and rub linseed oil on them with the rag. Try not to get it on your clothes, and wash your hands when you've finished this step. If you have sensitive skin, wear rubber gloves. Also, linseed oil heats up as it dries, which can cause your rag to spontaneously combust. So rinse your rag out very thoroughly. More information can be found on the container the linseed oil is in. once you've gotten a thin, even coat on your dowel, insert it into your 3/4" PVC pipe. I've found that the best way to do it is to push it in as far as it will go, then bang it against the ground, dowel-first, until it goes in completely. Cut off any excess dowel sticking out of the pipe.
Step 3: Making Your Crossguard.
Step 4: Attaching the Crossguard and Pommel.
Step 5: Padding.
First, take one of the lengths of Insulation and open the slit (with your thumb, like an envelope), then cut about a 3/8" slit off one side of the slit. Then cut the end into a point using 2 45-degree cuts, as shown in the first picture. Notice that the slit is at the end of one of the points. Position the sword as shown in picture 2, and put the double-sided duct tape on both "edges" of the sword. Make sure the 2 pieces of tape don't overlap. Now attach it to the core so that the points on either side are on the flat of the blade, as seen in picture 3. (Picture 3 also has the crossguard padded). Put some pieces of regular duct tape every few inches along the slit for added security.
Then cut 2 pieces of insulation, each about 2 inches longer than the length from the center of the crossguard to the end of it. Cut them into points, just like the piece you just put on the blade, except make the slit sit between the points instead of on one of them. Attach them to the sword just like you attached the last piece, but make the slit facing down (towards the pommel).
Now take 3 pieces of foam, each a little longer than the distance from the end of your core to the end of your foam on the blade tip and crossguard. cut one edge of the slit at about a 30 degree angle, as seen in picture 4. trim some foam off the other edge of the slit, roll the piece up and see if it fits in the tube of foam at the end of the blade (or crossguard, whichever one you're working on.) If it doesn't, trim a little more off the slit and try again. Once the pieces are in the ends of the blade and crossguard, trim them flush, as seen in picture 5.
Now take the other pieces of insulation and cut them to the same length as your first blade piece. Slit them in half down the middle, as seen in picture 6. Then cut one end of each piece in a sort of fish-tail, like in picture 7. Tape them to the edges of the blade, holding the piece up to un-curve it where it meets the tape and help you keep it centered on the edge. see picture 8.
Once you've gotten as many layers as you want (I use about 3-4, depending on the weight of what i'm making), take the sword like in picture 9 and slit those little corners off the flat of the blade like you're filleting a fish, using a sawing motion. Pictures 10 and 11 are pictures of before and after I did this.
Finally, trim the end as shown in picture 12 and you're ready to wrap your sword! For me, wrapping isn't a precise science. I just put duct tape on every bit of foam I see until I can't see any foam.