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How to make your own cowling

One of the most disappointing aspects of the GWS Pico Moth has been the stock 2 piece cowling that comes with the kit. Not only being cumbersome to join but the plastic itself is extremely brittle and tends to crumple beyond use on its first impact with a hard surface. What I did was use the kits cowling as a template to produce my mold by using sticky tape to close all the holes including a raised ring around the rear of it to extend the mold past the rear edging. I then stood it on its nose and filled it with Plaster of Paris. I also inserted a short length of large diameter dowel into the centre of the plaster while wet to provide a handle to use when working with the mold later.

Step 1 - The bottle


I select any bottle that meets the size requirements. I aim for a diameter that allows a small amount of space all around the mold. Since 1.25 litre soft drink bottles are readily available in my household, they get used the most often.

I start by cutting off the neck with a small cutting saw.

Then I peel off the label and cut the bottom of the bottle off using a pair of large scissors leaving plenty of excess plastic.

Step 2 - Tools to Use


The only tools I use in the formation of the cowling is a heat gun and a Clamp . The heat gun is the type sold at hardware stores that can be used for paint stripping. It gets very hot and can easily scold so be careful. The Clamp type I use is the one that has a tension trigger so you can squeeze the clamp tight with only one hand - it makes the job easier.

Step 3 - Creating the cowling

Firstly, insert the mold into the bottle and align the prop hole area as closely to the neck opening as possible. Then clamp the other end of the bottle to the handle. If you didn't make a handle - the plaster is strong enough to allow you to clamp the bottle to it without breaking. I have done this with this actual mold without incident. I do stress clamped - not tightened beyond belief.

Step 4 - Heat shrinking the bottle

The clamping of the plastic stops the bottle from shrinking past the end of the mold - as it will do - trust me! Once you heat shrink the end of the bottle around the base of the mold you can remove the clamp. This also allows for easier manipulation of the mold as you will be constantly turning it.

Apply heat with a back and forth motion all over the bottle area to uniformly shrink the bottle until it is nice and tight against the mold. I try to catch the light against the surface and look for ripples and bumps and work my way around in a final hunt for them so the surface ends up nice and smooth. You should end up with a result as in this image.


The next step is to draw the cowling outline from the imprint the original left on the mold. Do this before removing the mold.

Step 5 - Removing the Cowling


Because we shrank the bottle over the mold we now have a really tight fitting result at the rear of the cowling. What we have to do is cut the plastic multiple times to make removing the mold easier. What I do is peel the plastic to just past the edge but not past the outline I just drew. By doing this - its like peeling a banana. Now cut the extra plastic away. The mold will still be on real tight so you have to push it out forcibly using any handy tool that wont damage the plaster via the neck hole. I use the rubber handle of a small pair of pliers. I also put a scrunched up towel on the table to catch the mold when it 'pops' out so it doesn't get damaged.

You should be left with something like this now.

Step 6 - Completing the cowling


To complete the cowling I use large scissors to cut along the outline I drew earlier, then sand out any rough snips to finish it into a nice curve.

I then cut the front excess off using a modelling knife.

Step 7 - Final steps and painting


The final steps are to take the new cowling and place it onto your Pico Moth. When in position, mark where the screw holes are and remove the cowling and drill the holes to suit.

Now you can paint it and mount it back on your model.

Congratulations, You are all done!


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