Hi all the instructables user!
In this document I will explain the steps I have taken to make the Predator Bio-Helmet. It took me about 3 months because I could not spend much time, but I'm still happy with the result.
First of all inform you that I have used the Google translator, so I do not know what language quality will be the tutorial. Even so, if someone wanted to translate it tell me and passed the document in Spanish. Thank you!
Step 1: Assembling Pepakura Mold
After surfing the internet and checking all available helmet models for Pepakura I got the attached model (BioCascoPrestore.pdo) which is the one that fit the most to my liking.
Once printed we cut through the indicated lines, we fold and paste for the areas indicated until we get the final model on paper. And take the time you need to stick it in a perfect way, because if we do not stick some area a little tilted, even if it is almost imperceptible, the rest of the model can be affected. It is advisable to use paper of 100gr of weight so that when we impregnate it of glue and resin to harden it does not deform.
Step 2: Hardening of the Bio-Helmete Predator Model
Once the paper mold is ready, touch it to harden it with acrylic resin, which can be found in any paint shop. As the resin is liquid the paper will be moistened for a moment and we can deform the model that has cost us so much paste. To avoid it, 2 cross-shaped sticks on the inside of the helmet, we give a layer of resin on the outside and wait for it to dry. Once dry we give it a second coat. With this we already have the outer layer of the Bio-Helmet of Predator completely dry and hard.
For the inner layer we will do a similar process: remove the sticks and apply a first layer of acrylic resin to have a consistent base. Next, and to provide our hunt of a good hardness and consistency, we will apply a layer of fiberglass.
Fiberglass can be applied in several ways. I did it following this tutorial, where it is explained to us that we must cut it into small pieces and stick it to strokes with acrylic resin. This process has to be done very fast to prevent the fiber from drying out before it picks up the shape we want.
Step 3: Cover With Polyester Putty
The next step is to cover our already hardened model with polyester putty, or also called automotive trimmer. There is the option to buy it with fiberglass included. In my case I used normal polyester putty.
This process is the most laborious of the whole project, so we must arm ourselves with enough patience and lots of sand.
When we buy putty, it comes with a catalyst, an agent that we add in a 2% mixture that causes it to harden as much as a stone. Be very careful with this because it acts very fast and in 3-5 minutes approximately begin to notice how the putty is hardening and every time we find it more complicated to apply it on the surface of the helmet.
We start applying putty on the outside of the helmet. We will do it little by little and not on the whole surface at one time since, as we have said, it will not give us time and the putty will begin to harden, and very careful since as they apply it is how it is going to stay. To extend it, we can use a rubber spatula and leave it as smooth as possible. Leave it to dry and proceed to sand it so that it is uniform. The drying time of the putty is about 40 minutes.
A very important trick, which will save us hours and hours of sanding, is to smooth the putty (before drying) with a brush impregnated in acetone. With it we will smooth the putty still fresh, to leave it without bumps and guromos and as smooth as possible so as not to have to sanding so many imperfections.
Once the part to be treated is dry, we proceed to its smoothening. For this process we will use 40-60 water-based sandpaper, gently sanding to remove thicker parts and bulk. Little by little we are changing the sandpaper, from 120, 180 and 200 until we have a smooth surface. For the last 2-3 sandpaper I advise to wet it in water as it will not cause us to eat so much putty and the surface is even smoother and smoother.
Once everything is to our liking and completely smooth, we apply a coat of primer spray, a type of paint that will help us to fill the holes that are there and also indicate the details that are missing for re-sanding or apply More putty. In this way we will have a more professional finish. We will apply sandpaper, or more putty and again spray of immediacy until the surface is completely smooth and if no holes to cover.
Step 4: Finishing and Painting Our Helmet
Come to this point you the quickest and easiest part to do.
As you can see in the photos, my helmet has a T-shaped mark on the forehead and another on the left eye, as if it were a scratch of an animal (or alien). These marks I have made with uan dremmel and fine cutting discs. Once marked everything I have smoothed shaped with discs and sandpaper, until it has remained as I expected.
This done, we cleaned the dust and remains of material of the hull and we apply again spray of primer, that will serve as basis for our printura. We let it dry and we have to paint. That glossy finish and the touch of color of the helmet I have realized it applying a base of paint in spray of matte black color and I have been applying another metallic gray spray, from a great distance to try to apply a blur between both colors. On the gray, and the parts that I considered, I applied the same black and gray spray, even the two spray at the same time, until it was painted as I wanted.
We let it dry and, finally, we will give that touch of wear and tear. To do this spray gray spray on a file of nails and, before it dries, we will apply it on the areas of our helmet that we want to scratch.
And with this we already have our Predator helmet finished. For the area of the eyes we can apply a metal grid that we will stick inside.
It remains pending the dreadlocks, which are still in process and the inner part of the helmet where we will place the head. As soon as I have it I will update the tutorial.
I hope I have been a great help !!