How to create a child-sized Stormtrooper helmet
So… I set out to print her make her a real one. Below are the steps for replicating it. The biggest challenges were patience (sanding, sanding, painting, sanding, …) and <10 year old motor control for final painting, but overall, she did an amazing job.

Steps

Design 3D printing and assembly Sanding and Painting Details Weathering Lenses

1. Design

First, you need to find the right 3D model of a helmet. I used Geoffro’s from Thingiverse. I printed the full helmet, not the individual pieces, but did 2 slices, so it ended up as 3 horizontal rings.

The 3d model for the helmet has a significant amount of detail. This one is also optimized to print well, where the edges are not too sharp and the details too fine to work.

Scaling the print to a child’s head

To design the helmet, the key calculation is the size to make it. When you think of a child, you mentally calculate that their head must be significantly smaller than an adult head, but that isn’t actually true.

Additionally, you need to actually scale the size of the helmet based on the difference in volume, not calculate it as a difference in height. For example, if you calculate that the child’s head is 70% as the size and scale the print down by 30%, you are actually scaling it down in 3 dimensions by 30%, resulting in the volume of the helmet being 70%*70%*7% = 34% of an adult helmet, which is about the size of a dolls head.

In the end, I scaled it to 89% of the adult print size, giving 79% of the volume and it fit my daughter well.

Printing cleanly

When printing the helmet, if you try to print it in one go, the entire interior of the helmet has to be filled in with support material. This can take more than a week to print and, because of its length, could run in to issues which make you restart.

You can see the two different shades of PLA for the 3 parts before painting.

The print does have multiple smaller pieces, but I found in a test print that it is difficult to get a smooth surface or glue all those pieces together cleanly as there is no internal skeleton.

Therefore, I printed the helmet using the single model in 3 horizontal slices. By aligning the top third with the indentation line around the back of the helmet it becomes almost invisible. The top slice was 213mm from the base and the bottom one was at around 105mm (Using 89% sizing).

When I finished the print, the “behind the ear” part of the helmet had roughed up layers and a small gap on the right side. I am not exactly sure why it printed it this way, but I would guess it had to do with scaling it down by 11% then optimizing the print, where it decided it was too thin.

Assembly

All 3D prints have slight imperfections in the flatness of the layers. I had to slightly sand the edges of each slice to get the 3 to fit together without gaps and then glued them on top of each other and waited it until it fully dried. On the first try, I just glued between the layers, but did not put any vertical supports. The result turned out to be very brittle and when someone dropped it, one of the sections came apart. I ended up adding vertical plastic strips between each section to increase the strength and then re glued it.

After that, I used bondo to fill the holes behind the ear and smooth out the seams at each layer. It wasn’t the smoothest job, which required sanding in a future step. I would suggest spending more time working to smooth and finish the bondo while it is still damp and not doing too much at the same time.

When it printed out, the chin area had an extra chunk of plastic which had to be Dremeled away before a head could fit in it.

White Base Sanding and Painting

As with any 3D print, the surface is never perfectly flat. This is exceedingly important for this project as the Stormtrooper helmet is meant to have a gloss white finish which will show any imperfections.

I started by using a finish sander to do a cut at sanding high ridges on the top and larger flat parts of the helmet and then moved to a quarter of a sheet of sand paper to scrape out any needs of plastic or sand off blemishes in layers. I did not try to flatten the outside, but instead was just preparing for the first coat of paint.

As there is no detailing yet, there was nothing to mask off for different colors, so I used a prime and paint flat white spray paint as the first coat. I dried it with a heat gun to speed up the process, allowing me to put multiple coats on in the same session. I then let it cure and harden for a few days so that I could sand it cleanly.

Using multiple white gloss primer coats removes the imperfections from the print.

When I sanded it, I worked to actually grind through the paint down to the plastic. This meant that I was left with a (mostly) flat surface where the ripples from each layer were significantly diminished. For this, I used a rougher 180 grit sand paper.

After that, I cleaned it with a wet cloth, let it dry and then used gloss white with multiple coats to create a smooth surface. I used a heat gun in-between light coats to allow me to create volume without worrying about drips.

I then repeated the sanding process, but with higher grit sandpaper and only by hand, to remove a set of small elements which became proud of the surface, washed and dried it again and then gave a few final light coats of gloss white again to finish the job.

Because the initial helmets in the movies were made with a vacu-form machine which could not make sharp corners, the removal of detail by adding many coats of paint looks fine, so don’t worry too much about putting on too much if you need to get it smooth. Just remember to do it in very light layers.

Detail Painting

For the rest of the details, I used a combination of hand brushing and masking tape cut into very narrow strips. The helmet uses combination of grey and black paint.

As my Daughter wanted to paint it herself, some of the detailing isn’t perfect and we decided not to add the blue stripes on each side due to their small size.

Online, there are printable stencils which I could have used, however I found that the 3d model didn’t quite match up with some of them, scaling was a challenge and my daughter wanted to actually paint it herself.

Sealing the whole design

Before you weather the design, you will want to spray the whole helmet in a coat of clear gloss spray paint and let it fully dry so that you are not affecting any of the surface painting on top of the base coat as it can scratch easily and also has a different gloss/Matt feel which you don’t want.

Remember to mask off the top black bar and the front black area first as they are meant to be a matt finish.

Details

The helmets have two black microphone tips on the chin and details on the ears. You can 3D print these, paint them and glue them on… or you can get them on etsy, where they have a lot more detail.

You can purchase mic tips with all the details made from molds of the actual ones used. They add a lot to the feel of the helmet, especially the mesh.

Weathering

Some people like a perfectly new helmet, but I always enjoy making them feel like they came off of a few years of normal and hard use. My daughter, hilariously, decided that her helmet must stay clean, so we ended up not weathering it like mine.

Good weathering feels like it is part of the prop. (Note: This is my helmet after weathering as my daughter decided her’s must stay “clean”.)

Dirt, grime and years of wear

For this, you need a metallic silver, black and burnt umber, which you can dry brush into the cracks of the helmet, let dry for 30 seconds and then wipe away. I recommend using the black as the first coat and then adding a brown coat on top because that feels like dirt on top of grease.

Once you have weathered it, think where the white might be rubbed away by year’s of use and use a metallic silver to create wear points. Try blending in your umber as a rust color in very small amounts.

Subtle weathering, adding wear-through on the white paint and multiple payers of grime really makes the helmet feel used… if thats what you are going for. (My helmet again, not hers)

Lenses

Finally, you need to get lenses for the helmet. If you want realistic ones, they were actually dark green in the movies, but any color will work. You are looking for transparent vinyl. Etsy has many sellers.
['Hans Lee']
['3D Printing', 'Costume', 'Stormtrooper', 'Star Wars', 'Props']