Making a Mold for a CZ 75 Shadow Line
So what to do when there’s no mold gun available for your specific gun? That’s the problem I had with my new CZ 75 Shadow Line. The only mold I could find was a replica blue gun, which was expensive, and would need lots of modifications to make it holster-mold ready. So I looked around YouTube for mold-making solutions. First, thanks and thumbs up to Red Feather Gear. Great, clear videos on the subject of making mold guns–extremely helpful.
Sometimes, however, no matter how good the video instructions, you have to fail before you succeed. The first mold attempt hemorrhaged epoxy like the devil taking a whiz, so bad, in fact, that the mold was a total loss. There was no way to clean it up enough to use again.
For the second attempt, with the luxury of perfect 20/20 of hindsight, I made a few changes. I won’t go into the details that Red Feather Gear has already covered well, only what I learned. Wherever I mention a specific product, I’ve included a web link to the source.
- I used 0.06″ polystyrene, available at Amazon. The poly was heated to 350 degrees, confirmed with an infrared thermometer. In the initial, failed mold, I had noticed that the detail was lacking. The first poly had been heated to 320 degrees, again confirmed with an infrared thermometer. The higher temp offered much better detail in the final mold.
- The mold release agent, Smooth-On Universal Mold Release, was applied by spraying it on a small paint brush first, and then applying the silicone based release to the interior part of the mold with the small paint brush. I was careful to keep the release off the edges that would have to be sealed.
- With the release agent in place, I snapped the mold together, and then wiped down all exterior seams with alcohol. If any release agent is in those seams, the hot glue will not seal the mold.
- I applied two layers of hot glue around the seams, and once applied, popped the mold in the freezer for a few seconds to dissipate all the heat left in the glue.
- I used foil tape, readily available at Home Depot, over the top of the hot glue. I worked it into the seams gently, and when the foil tape split or tore, I placed another piece over it. Two layers are better than one.
- When cutting back to the center-line on the first half of the mold, I did a rough cut first and then used a 12″ disc sander to clean and flatten the edges back to the center-line. When the second half of the mold was made, the prep on the first half made a much better fit that was easier to seal.
The epoxy used to fill the mold was from Reynolds Advanced Materials, in Tempe, Arizona. Great folks, extremely knowledgeable and helpful. Because the mold will need to withstand high Kydex temps, they recommended, Smooth-On EpoxAcast 670 HT. Its more challenging to mix, not one to one, and will require a scale that measures in grams. The ratio on this product is 100A:16B.
The second mold was perfect–great detail, no leaks. I let the epoxy cure for two hours before removing the polystyrene mold. While removing the mold, one half of the polystyrene shattered and will not be usable for a second mold. I used this method, however, because I only needed a single mold of the gun. If I was in the mold-making business, I’d have made a rubber-mold that could have been used over and over. Red Feather Gear also has videos on that process. The CZ 75 Shadow Line took about 10 ounces of material by volume. One kit of the EpoxAcast 670 HT was a little less than fifty bucks, and should be able to mold three to four guns, depending on the size of the gun.
So today I’m going to mold a double magazine carrier for the CZ 75 Shadow Line. I’ll let you know how it goes!