This is a how-to guide that I made when constructing my own wooden bokken. I read a great how-to on this site, but it didnt show me how to make the Tsuba(or guard) So I had to make one up myself.
For the Sword how-to, the link is here:http://www.instructables.com/id/EMVOZXMBO2EP286GNG/
I will also make a sword guide similar to TTF's method in the future
Step 1: Making the Notch
For the tsuba to fit into the handle nicely, you must first construct a notch. This can be done with a dremel tool, or by had with a chisel.
The first step is to mark where the notch will be on the bokken. If the bokken is katana length, use 4 hand over hand measures. Wakizashi, 2 and a half. Tanto, one and a half. Judge the hand method to the length of the sword.
The second step is to take your handle material(any kind of wood is ok. But it must be 1/4" or larger. Anything thinner will break.) and trace the outline on the bokken.
Afterwards, take your chisel or dremel tool, and cut out between the markings. using a wood rasp also works.
Step 2: Cutting the Tsuba
Next, you have to cut the material for the tsuba. I myself used Oak Screen Moulding, which is 1/4" thick, and has one rounded corner. Measure out the length you want the tsuba to be, and make sure its a bit larger, and cut it. place the cut piece onto the rest of the stock, then mark and cut.
Step 3: Measure the notch length
Place the cut piece along the notch. Then mark the area from the inside of the notch to the outside of the bokken. Once you mark the first piece, take both pieces together, and place the bokken cross-section in the center and mark a square around it.