A leather sheath is a classic option for your favorite fixed-blade hunting knife, but it's also not waterproof or as durable compared to some modern day options. Try making a Kydex sheath instead.
Heat a sheet of Kydex to 350 ˚ F. Be careful—overheating will ruin the material. Wrap the heated piece around the spine of the knife, and using neoprene foam for padding, squeeze the Kydex in a vise or with clamps with as much pressure as possible. Let cool and set for 12 to 15 minutes.
Trace the desired shape of your sheath with a colored pencil. Be sure to leave at least an inch margin around the knife for riveting. Cut out the shape with a band saw, scroll saw, or a pair of sheet-metal snips. Sand the edges smooth and straight.
Drill out ¼-inch holes evenly spaced along the edge of the blade. Press rivets slowly and smoothly to prevent splitting. Bolt on desired hardware, being sure to apply thread locker. You can also run paracord through the rivet holes for lashing the sheath to something.