One of the older workshop tips for scale modelers is home-made vacuum formed plastic parts. For many, Vac-forming is an advanced modeling technique, and it is great for making all sorts of scale accessories. These include small panels, fairings and cowlings, scale bombs and drop tanks, and even smaller items like scale goggles for your pilot figure. One of the best sources for information on vacuum forming is the book, “Do it Yourself Vacuum Forming for the Hobbyist” by Douglas E. Walsh. http://vacuum-forming.com/. It’s loaded with information if you want to really get into the process including making your own Vac-forming machine.
I have used some of the techniques mentioned and have simplified the process to suit my own scale modeling needs. Here’s how I made some 1/3-scale goggles for my Mini-me pilot figure.
To make the goggles I first scanned a pair of vintage goggles and imported the image into my CAD program. I then traced the image to produce a working drawing that I then reduced to 1/3-scale. Using the drawing as a reference, I made a plug from bass wood so I could vacuum form the lenses.
My Vac box is nothing fancy as you can see. I made a simple 12×16 inch wood box about 4 inches deep and topped it off with a sheet of plexiglass (1/8-inch thick.) I drilled 3/32-inch holes on 1/2 inch centers and then screwed and sealed it to the top of the box. I used simple stick on-foam weather proofing strips around the top to form a seal when the plastic sheet is placed on top of it. I drilled a hole in the side of the box and added a plastic fitting that matches up to my vacuum cleaner. It works great hooked up to a regular vacuum cleaner.
I placed the plug on top of a small piece of window screen and seal around the top of the box with painter’s tape to minimize the area. I now place the box ready to go, next to the kitchen oven. (I do have to get permission from my wife for this!)
I then taped some thin clear plastic to a carrier sheet made from 1/8 inch plywood. Clear plastic is available at most hobby shops and for small parts like this, I use 0.015-inch thick clear plastic. The opening in the carrier sheet is made so it clears the plug by a good inch to inch and a half all the way around.
Place the plastic and plywood carrier in an over as shown and heat in a 350 degree oven until the plastic starts to sag through the opening in the plywood. A droop of about an inch to inch and a half is about right.
Once the plastic is ready, switch on the vacuum and quickly move the plastic and plywood sheet onto the top of the plug (Plastic side down,) and press down firmly. The vacuum will suck the plastic down into place and the plastic will start to cool off quickly. Should you find that the plastic does not form smoothly over the entire plug, you can drill a small 1/64-inch hole in the area needing more vacuum.
Don’t force the plug out of the formed plastic. When the plastic has cooled enough, the plug should fall out easily on its own.
Here’s the formed lenses. The flash makes the plastic look a little foggy, but it is very smooth. Be sure to clean your plug completely of dust. You can also apply a thin coat of paste wax to seal and smooth the surface of a raw wood plug.
To make painting masks for the goggles, simply trace the outer edge of the plug with a soft pencil using some tape.
Here is the mask on the plug with the waste tape removed.
Add the tape masks to the formed plastic lenses, burnish down real good and spray with a mist coat of plastic primer. After the primer dries, mist a light coat or two of silver paint. Be sure to add a protective coat of tape inside the lenses to guard against over-spray.
Here are the finished goggle lenses. I was going to use this stick on foam tape as a skirt, but you can form it also from polymer clay.
Here my pilot bust with goggles added, (use clear setting Zap Canopy Glue,) awaits some more detailing. To make the goggles lay flat against the rounded helmet skirt, use a covering heat gun to gently soften the center of the goggles, protecting the lenses with your fingers while pressing the goggles in place.
These same techniques can be used to make all sorts of parts from formed plastic. The sky’s the limit!