Kydex is an acrylic and PVC thermoplastic sold in thin sheets. Heated, it goes soft and floppy like leather; pressed around an object and left to cool, it keeps that shape exactly. That makes it the standard material for knife sheaths, flashlight and multitool carriers, and holsters of every kind. It is light, shrugs off water and mud, does not rot or stretch like leather, and holds an item with a positive click that is known as retention.

This guide builds a two-piece holster, formed half by half and riveted together, for a fixed-blade knife or a tactical flashlight. The same process works for any rigid object. A simpler single-fold pouch for a flashlight or spare battery is good practice before trying a two-piece holster.

What you will need

Kydex sheet, blank eyelets and rivet tools are sold by knife-making suppliers.

• Kydex sheet, 0.080 inch thick for holsters (0.060 inch is easier for small sheaths)
• A box cutter or utility knife and a straightedge
• A ruler or a cutting board with a grid
• Two sheets of closed-cell sheath foam, about 12 by 11.5 by 1 inch
• Two flat wood boards a little larger than the foam
• Two or more wood clamps
• A pencil or silver marker

• 8 eyelets, 1/4-inch length, with a matching flaring die and setting tool

• A drill with a 1/4-inch bit
• A dedicated toaster oven or shop oven, and a baking sheet
• Heat-resistant gloves
• A heat gun (optional, for touch-ups)
• Files, a sanding block and sandpaper in coarse and fine grits
• Masking tape
• The item the holster is for

Laying out and cutting

1. Tape over the whole blade of a knife, edge and point included. It protects both the edge and your hands during pressing, and adds a sliver of clearance so the finished holster is not too tight.
2. Lay the item on the sheet that will sit against the body. Mark a border of about 2 inches along the side where the rivets will go and about 1 inch past the tip or end.
3. Score along the lines with the box cutter, two or three firm passes, then bend the sheet over the edge of a table and snap it along the score.
4. Trace the item’s outline on the cut piece. Kydex has a textured side and a smooth side; draw on the side that will face inward, so the textured face ends up outside.
5. Mark a scallop at the handle end where fingers need room to grip, then score and snap it out.
6. Cut the outer half the same way. It needs no scallop.

Heating and pressing

Set up the press first: a board, a sheet of foam on top of it, the item nearby, the second foam sheet and board ready, clamps open.

1. Heat the oven. Hobby makers usually run a toaster oven at about 300 to 325°F for sheet of this thickness. Some older guides give 220°F with the oven door ajar, which is too cool for most sheet to soften properly. The manufacturer’s forming guide says the sheet itself should never go above 400°F.
2. Put one half on the baking sheet in the oven. Warming the foam near the oven helps, because cold foam pulls heat out of the plastic and the detail comes out soft.
3. Check it every minute or two with gloves on. It is ready when it droops like a wet noodle when lifted by one corner, usually after a few minutes. If it bubbles, smokes or smells sharp, it is too hot; take it out, turn the oven down and ventilate the room. Overheated PVC gives off irritating fumes, which is also why a food oven is the wrong place for this.
4. Lay the soft sheet on the bottom foam, outline up, and set the item on it, lined up with the outline.
5. Put the second foam sheet and board on top, and clamp the stack down hard. More pressure gives sharper detail.
6. Leave it in the press for about 15 minutes, until the plastic is fully cool.
7. Repeat with the other half, pressing it from the opposite side.

Trimming and riveting

1. Draw the final shape on both halves, leaving about 3/8 inch of flat margin outside the formed pocket for the rivets. Cut away the rest.
2. Put the item back inside, clamp the two halves together and mark rivet positions along the margin, about an inch apart and close to the pocket, where they tighten the grip.
3. Drill each hole with the 1/4-inch bit while the item is still in place, so the halves stay aligned.
4. Set the #8 eyelets with the flaring die, a firm blow at a time.
5. Where the halves do not quite line up, file or sand the edges until they are flush, using a belt sander, a file or coarse paper. Wear a dust mask.
6. Finish with fine-grit paper and round every edge so it does not wear through clothing.

Belt loops and final fit

Make belt loops from strips of Kydex about 1.5 inches wide, heated and bent around a scrap of wood the width of the belt, then riveted to the back of the holster. Two loops spaced apart hold it steadier than one.

Retention can be adjusted afterward. Warm a small area with a heat gun and press it in with a gloved thumb to tighten the click, or warm it and flex it out slightly to loosen it. A light pass of the heat gun over the edges also lets them curve in toward the body so the holster sits flat.

Test the finished holster over and over before trusting it: the item should go in with a click, stay put when the holster is turned upside down and shaken, and come out with a firm pull on the handle.