This is my very first Instructable, after watching and reading so many. Please give me some feedback, so I can do better on my next one.
There are videos out there that show how to do this, but another person I know asked if I could do a tutorial for making plastic guns from casting resin. This same process can be used to make copies of about anything you want. This method produces a great amount of detail in the finished product and takes about 30 to 45 minutes to complete.
I build leather holsters, belts, wallets, etc..., so I needed to use my customer's gun, to mold the holster to it. The problem was that I had to keep their weapon for several days to accomplish that and because the leather is wet when I mold the holster, I needed to wrap the piece to keep it dry. I looked at purchasing plastic guns for this, but a cheap one is $50 or so. That cost quickly ate into any profits, so, because of my cheapness...errrr, thriftiness, I decided to make my own.
Step 1: Vacuum Box and Frames
I made my own vacuum box to form Kydex for the hybrid holsters that I make. There are numerous videos out there on how to make this. I made mine from 3/4" plywood, but I would recommend 1/2 or 3/8 melamine or birch plywood, due to weight. Mine is 12 x 14 inches, with 3 1/2" sides. These dimensions give me ample space for anything I want to mold. I used High Impact Polystyrene (HIPS) Plastic Sheets that are .020" thickness. I bought mine in a 4'x8' sheet through Amazon for about $24, but there are several places to get it. Attach the HIPS to the frame using a staple gun. Staple about every 2 inches or closer, as the HIPS shrinks when heated. You will need one of these for each side of the mold.
I use a small Shop-Vac to create the negative pressure in the box. Mine is only a 2.5 hp, and does the job with no problems.
Step 2: Preparations and Forming
First and Foremost!! Ensure that any firearm is cleared and empty before using them in any project. Then check it again. And again, if you are not sure.
Tape any large openings on the gun. The vacuum will pull the HIPS down into the spaces, and can make it difficult to get the mold off the gun. Always keep the magazine in the well, since this is where you will fill the mold from.
Preheat your oven to 350 degrees F. I used a couple of 2 x 4's to hold the frame up off the rack. The HIPS will sag when it gets warm, so this is essential. It only takes 2 or 3 minutes to get the HIPS soft enough to suck up around the gun when you get ready to form the mold. Turn on the Shop-Vac before you take the HIPS out of the oven. When it's soft enough, just take the frame out, flip it over and lay it on the gun. It only takes a few seconds for the HIPS to cool, so this step needs to be done very quickly. The good news is that if it doesn't work the first time, you can usually just put it back in the oven to soften it and try again.
Step 3: Cutting Out the Mold
When it cools cut the form out of the frame with a rough cut, then trim closely to the gun, just below the edge. I use a curved blade, as this allows easier cutting on the small radii (radiuses??) If you're happy with that, turn the gun over, with the HIPS still on the gun and repeat the steps to form the other side.
Step 4: Assembling the Mold
The most difficult part of the whole process is getting the gun out of the mold. I use a modelling tool to gently pry the two sides off the gun. Put the two sides back together and tape the seams well. I have found that metal duct tape works best, but about any heavy tape will do. Do a good job here to prevent the casting resin from leaking out through the seams. Cut out the bottom of the grip to make an opening to pour the resin into the mold.
Step 5: Pouring the Mold and Finishing
I place the mold upside down in a vice, with the barrel end tilted down somewhat to help the casting resin fill all the little spaces. Don't clamp it so tight that it deforms the mold, but it needs to be firm enough so the mold wont move when pouring. Since I don't have any resin in my shop today, I can't show you that part, but I usually just go to Hobby Lobby, Michael's, or any craft shop to get the kit, or buy it online. I use the Alumilite Amazing Casting Resin 16 oz kit, which costs anywhere from $12 to $18, depending on where you buy it. I can usually get two guns from one kit.
Follow the directions for the casting resin, mixing in a one to one ratio. You can mix in color to suit your desires. The thing to remember here is DON'T mix/whip the resin quickly. This will create air bubbles in the finished product and gives it a very rough texture. Stir slowly until the two parts are completely mixed. ( about 1-2 minutes) Slowly pour the resin into the mold. Tilt the mold back to level at the end of the pour, so the grip end will be flat. The resin heats considerably when curing, so make sure to wear gloves when handling the mold after the pour. The resin sets in just a few minutes. Use the left over resin in the cup to gauge when to remove the mold.
Take your time removing the mold from the gun, so you don't damage the piece. Trim and sand excess plastic from the gun for a smooth, finished product.
Any comments and feedback are welcome. Thanks!