A Katana is a traditional thin and curved Japanese sword. As it is usually very sharp, a scabbard is needed for safety and to protect the blade. Here's how I built one using common tools from the workshop to replace an existing poor quality scabbard.

Step 1: Materials and Tools

2 Hardwood boards
Wood glue
Jigsaw
Router
Spokeshave
Stain
Varnish

The scabbard is made from 2 pieces of wood glued together with a thin opening to accommodate the blade. The first task is to find 2 hardwood boards with the right dimension. You need to be able to draw the contour of the blade plus 1/4" all around it. I used left over bamboo floor boards.

Step 2: The Shape

Designing the shape of the scabbard is quite straightforward. First, you'll want to place the blade flat on one of the boards. Then, tape a piece of wood 1/4" wide against a pencil and use it to draw the contour of the blade. You should end up with a shape roughly 1/2" wider than the size of your blade. Repeat this operation on the second wood board.

You can now cut the boards outside the pencil line using a jigsaw.

Step 3: Carving the Blade Pocket

Once again, place the blade flat on the board, but this time, trace the exact contour of the blade with a pencil. Do the same on the other board.

Measure the thickness of your blade (just past the handle) and divide it by 2. This is the amount of wood you need to remove to get the blade to fit into the scabbard.

Using a hand-held router, set the depth of the bit to that dimension (add a little bit more to get the blade to slide nicely). You can now carefully carve the wood. Make sure you stay inside the pencil line.

The previous scabbard had a plastic ring to retain the blade so I had to carve a deeper pocket for it.

Step 4: Glue the Boards

Before gluing the 2 sides together, I applied a bit of wax where the blade will slide. This ensures a fluid movement of the blade.

Use some wood glue to assemble the 2 boards. Once dry, you can smooth the edges using a spokeshave. Be careful not to carve too deep as you don't want to cut through the thin walls of the scabbard.

You can then use a file and a series of sand paper (grit coarse to fine) to get the surface free from any asperities.

As I am making the new scabbard from an existing one, I am reusing the plastic and metal parts. You don't need this if you're building one from scratch.

Step 5: Results

Use some stain and varnish to give your scabbard the look you want. Bamboo is a pale wood so I used a dark walnut Danish oil and protected it with a few coats of wipe-on polyurethane varnish.

I reused the metal covers from the previous scabbard and glued them back on both ends of the new one. However, these are purely for a decorative purpose and they are not needed to build your own.