The usefulness of this model, depends on your larp system and rules. The design is for a "sufficient force" larp combat system. For a bare minimum type combat system you can get even more creative. For a full force system, it will do as well, though its not perfect - the blade might get damaged and a bad swing could get someone's head ringing(or cause a nose bleed) if both participants are not having proper protection.
What you need!
BUDGET - about 10-15$ probably less. Rest will be cheaper because some things like the duct-tape can be used another dozen times.
Pipe insulation foam. Thats fairly simple to find.
Polypropylene pipe for cold/hot water. Id say around 20-25mm diameter or 1 inch, depends on how thick and tough you want your sword to be. PVC pipes are not a good idea. They, like bamboo might shatter(bamboo WILL shatter eventually) leaving your project ruined, and you swinging something with jagged edges around. Polypropylene pipes are much thicker and they tend to bend slightly, which makes them far more resilient. For 3 years I've seen only 1 polypropylene boffer sword snap and that was because it got tangled in the armour of two heavy weights while they were bashing each other.
The rest is duct-tape, and tools - scissors, knife and so on.
First things first - you get a pipe for your boffer sword that is the desired length. Let's face it, you probably won't get it right from the first time. Why? Because you will need to try several times to find what size of a weapon suits you best. I find myself making annoying misses with someone else's weapon that's just a few inches shorter than my own, simply because mine is...well mine - it fits in my hand perfectly.
Keep in mind - the pipe will be 1-2 inches shorter than the completed boffer - the pommel and tip will add more to it.
Once you got it straightened out, Start marking strips and get ready to cut them out.
Don't make them too wide, they should be just enough to cover your pipe - so depending on pipe diameter - about 20-25mm wide.
Mark it to the bottom with the marker - You don't want to make mistakes which will leave the blade uneven. It won't stay well on the pipe and you might hit someone with the flat which will hurt.
After that - its time to cut out the strips for our new larp sword!
Once you get the strips, its time to attach em to the pipe. Use tape to keep them in place and make sure they are all perfectly lined up. Same reason as with the cutting!
The point where both sides of the larp sword are done is where the 95% stop, wrap it in duct tape and look at it proudly. Its all well and good, but I say we take this a little further.
Grab the scissors and shape that blade a bit more.After all we are making a singe edged sabre.
Now it looks a little better, but still when people see they'd say Meh another boffer. So we take this further.
So we give our new larp sword a real edge. Use a marker to point out what needs to be cut, then grab a paper knife and slowly shape it into an actual blade.
And voila - now thats something you can use with pride.
Or this one, which shows at least some effort, but its still a long way.