Cursed Pirate Treasure Chest

We LOVE pirates and one of our favorite video games is Sea of Thieves, a game about pirates! The art style of this game is absolutely incredible and we got inspired to recreate some of the pirate props from the game. In our search, we came across an epic Sea of Thieves-inspired concept art created by artist @DaltonPenc (https://www.instagram.com/daltonpenc/) and decided we had to try to create this in real life! (You can find the concept art here: https://www.seaofthieves.com/community/forums/topic/53045/design-for-a-new-treasure-chest)

We recommend watching the YouTube video above while you read the article!

This project is made from XPS insulation foam, EVA foam, and features 3D-printed skulls and hardware. The magic comes to life thanks to glowing LED eyes powered by an Arduino Uno and eerie smoke from a hidden Microfogger. We’re so happy with how this treasure chest prop turned out - it’s the perfect addition to our Halloween pirate display and we can’t wait to show it off this season!

Supplies

MATERIALS:

1" & 2" XPS Foam - https://amzn.to/3wlfjdv

6mm, 10mm EVA Foam (HD Foam) - http://bit.ly/2NECyrU

Microfogger - https://vosentech.com/index.php/product/microfogger-3-lite/ (USE CODE 'wicked' for a free circular diffuser with purchase)

Neopixel LED Strip - https://amzn.to/3iGnOYl

Arduino Uno - https://amzn.to/3uq0io4

Battery Pack - https://amzn.to/3JGXCZw

Barge Cement - https://amzn.to/3L1lFmf

Clear Gorilla Glue - https://amzn.to/3wqdQCO

Starbond CA glue - https://amzn.to/3ufbjIX

Starbond Accelerator - https://amzn.to/3qKp3un (optional)

Wood Glue - https://amzn.to/3iqIVhu (optional)

Hot Glue - https://amzn.to/3qz1vbG

1/4" Irrigation Hose

DAP Alex Plus - https://amzn.to/3L5kVMT

Drylock Extreme - https://amzn.to/37DhKh6

Rub n Buff Silver Leaf (2 pack) - https://amzn.to/3L4BPv4 (optional)

Acrylic Paint (Plum) - https://amzn.to/3wnLRDw

Obsidian Metallic Paint - https://amzn.to/3imHIrt

Blue Tape - https://amzn.to/3IxhME8

Toothpicks - https://amzn.to/3NmNS90

PLA (3D Printing Material) - https://amzn.to/3ixndIH (optional)

TOOLS:

Utility Knife - https://amzn.to/3wy4rsQ

Square - https://amzn.to/3DaxHam

Straight-Edge (Ruler, etc.) - https://amzn.to/3JFOGUq

Hot Glue Gun - https://amzn.to/3qz1vbG

Dremel Kit - https://amzn.to/36pT8YU

Airbrush (optional)

3D Printer (optional)

Flathead Screwdriver

Paint Brushes

*** Some of these are Amazon Affiliate links. Clicking them helps support projects like this! ***

Step 1: Cutting Your Foam Pieces!

The first step was to cut out all the individual pieces of foam! We used a sharpie to mark all the lines on the pink foam and then used a straight-edge and a very sharp utility knife to cut out the pieces.

Both the XPS and EVA foam is extremely easy to cut if you have a sharp knife. Having a few extra blades on hand to switch out when they get dull is a great idea. An even better idea though is to learn how to sharpen your utility knife blades!

We measured and cut out all of our XPS (pink) foam pieces as well as several 2" wide strip of 10mm thick EVA foam.

Step 2: Cutting Your Angles!

All of the pieces of the box come together with mitered (angled) corners, so we needed to make a bunch of angles on the ends. We also had to cut them on the bottom so the pieces would sit flat.

With the thinner EVA foam it's possible to angle your knife and cut bevels/45-degree angles, but with the 1" thick XPS foam it's very difficult. Therefore we find it easier to cut the angles after we have the pieces cut.

If you have a bandsaw or tablesaw, those are great options, but there's an easy way to do it by hand!

First, use a square to mark your 45-degree lines, connect them with a straight-edge, then use your knife to remove as much waste as you can inside the lines. Clean up the final angle with a surform tool/rasp. Bam! Perfect 45-degree angles without a saw!

Step 3: Making the "Wood Grain" Texture!

This part was so fun! We took the very flat face of the XPS foam and used a knife and screwdriver to make it look like wood grain. This was done in two parts.

First, we cut a large line in the middle to represent the two planks of wood. This was done with the knife.

Second, we used a flat head screwdriver and pressed it into the foam and pulled it across in a wavy line. It was very fast and looked amazing. YOU SHOULD TOTALLY TRY THIS.

Step 4: Gluing Up the XPS (Pink) Foam!

The first of several glue ups was the main chest itself.

Important: The pink XPS foam will get eaten away by any glue that has acetone or any kind of solvent in it. There are plenty of glues that work fine but make sure to test the glue you're using so it doesn't destroy your hard work!

We like to use clear gorilla glue to glue up pink foam. You simply spray a little water on the pieces, spread your glue, then we use blue painter's tape to hold the parts together while they dry.

Step 5: Making the "Corners"!

While the chest glue was drying, we made the faux metal "corners" from 6mm EVA foam. (Even though the corners were bones in the concept art, we wanted to keep this part a bit simpler.) The EVA foam is more appropriate for smaller parts like this because it's flexible and can be easily shaped. The pink foam is rigid and better for the "wood" parts. We started by cutting small strips and then beveling the edges with a 45-degree cut so we could glue them together to make a L-shaped vertical corner pieces.

To glue EVA foam pieces together, it's MUCH easier thank the pink foam! You can use Barge or any other contact cement. This kind of glue is applied to each surface, then you let it dry for about 5 minutes. Once both pieces are dry, you can stick the pieces together for an instant bond. This is amazingly useful because its so fast but this type of glue will destroy the XPS foam so you can only use it on the EVA foam!

We also cut some more pieces of 10mm foam and did the same thing for the outer layer of the corners which we later glued onto the outside with Barge.

Step 6: Gluing Up the EVA (Grey) Foam!

Once the glue was dry on the pink foam, we then glued on the grey EVA foam strips for the metal banding and the vertical corners. This will act as the faux metal that protects the corners and edges of the chest.

To glue the EVA foam to the XPS foam, we recommend using the clear gorilla glue. If you watch the video, you'll see we made some mistakes here which we learned from! Clear gorilla glue is simplest and worked best.

We did this in two phases, letting the horizontal strips dry completely and then adding on the vertical corners and outer corner pieces.

Step 7: Making the Hardware!

While the glue dried (again...:) we worked on the 3D-printed hinges and hardware!

Using the concept art as guidance, we modeled several parts in Fusion 360, including a couple of "print-in-place" hinges. These are fascinating parts because they print as a single piece but then function as a working hinge! It's really cool. The parts are large and stylized to represent the style we wanted. We printed hinges for the back and latches/hasps for the front as well.

By the way, these 3D print files are available on our Patreon if you're interested!

We have some fun looking 3D Printing timelapses of this process in the main YouTube video!

Step 8: Cutting Hinge Mortises!

For the hinges and latches, we cut "mortises" which are essentially the holes where the hinges will go. Cutting the pink foam is so easy that we could just mark the area to cut out and then remove the waste with a sharp knife as before.

Very fun, fast, and easy to do accurately! We cut mortises for the two back hinges and the two front latches.

Step 9: Texturing the "Metal"!

Next we used a knife and a rotary tool with a sanding drum to rough up the edges and surface of the grey EVA foam so the "metal" would look worn.

We LOVE this part of the process because you can really tell a story with the scars and bruises you put on the prop. You can imagine Pirates battling over the treasure or a Kraken attacking the ship and battering the chest around as it gets scarred and bruised up. Maybe it's been sitting under the ocean for a hundred years or who knows! You can be really creative and make it look awesome.

The foam cuts like butter so with a simple sanding drum you can remove material really easily.

Step 10: Final Paint Prep!

The final surface prep before painting was two quick steps. First was to use some "DAP" caulk to fill in any gaps or mistakes we made up until this point. Second was to "heat seal" the EVA foam, which gives you a smooth surface and helps prep the surface for painting. This is done with a heat gun or blow dryer and passing the gun across the surface very briefly.

If you build something like this, be careful where you aim the heat because it will quickly melt the pink foam!

Step 11: Painting - Base Coat!

Painting! Now that the surface is completely prepped we can start with a sealer, which for us was Drylok Extreme. It's actually a masonry sealer that is perfect for outdoor props because it seals and waterproofs the surface while making it easily paintable. Drylok is usually a sandy texture which is great for doing fake stone, but for the smoother surfaces we used Drylok Extreme, which is the same protection but without the grit.

For the base coat of color on the "wood" we used an acrylic paint color called "Plum". Being faithful to the color of the wood in the concept art was fun, this color was amazing! It took three coats on top of the white Drylok for full coverage to get a deep purple.

For the "metal", we used an obsidian colored metallic acrylic paint which has a great sheen to it. We also used this paint on the 3D-printed "hardware".

Step 12: Painting - Details!

Once the base coat was dry it was time to add details!

We start with a "wash" which is watered-down black acrylic paint. We create a very watery mix and essentially "wash" the surface with it. It seeps into all the small cracks and holes so when it dries it gives the dark paint remains in the cracks and crevasses. However, when it's done it will look VERY dark, so now we need to lighten it up with some drybrushing!

Drybrushing consists of using a rigid flat brush and very lightly brushing the edges and areas you want highlighted. With just a tiny light brush across the edges, it pops the highlights and creates a lot of depth.

With the base coat, wash, and highlights, the piece was looking phenomenal at this point. We were so excited!!

Step 13: Making the Skulls

With the chest painted, it was time to move on to the skulls and effects. Although we could have used plastic skulls from the big box store, we decided to 3D print our own skulls in the very distinct Sea of Thieves style. We found an artist online who has modeled some exceptional skulls and purchased the models from him!

You can find their work here: https://cults3d.com/en/users/Jhonny_A/creations

There is an AMAZING timelapse of 3D Printing the skull in the YouTube video!

Once printed, we had to figure out how to position the skull on the box (and eventually how to attach it). We did this by using a 3D app (Maya) to position the skull model against a mockup of the box and figure out where it was going to go, we then used a laser line to mark where we thought the lines should be. From there we used a dremel to cut the skull in half so it could be placed on the box.

For the front skull, there is going to be lights and fog effects coming out of it so we needed to hollow out the eye sockets and make some cracks. Jaimie drew a crack pattern and Jay cut the cracks out using the Dremel.

What we learned was that in hindsight we should have printed the skull in it's "final form" instead of doing all this cutting and shaping. Our big problem was we were making this up as we went along and it cost us a LOT of time. Much better to preplan and print exactly what you need!

If you use a skull from the store, you could just cut it and fit it normally as well. It just takes some adjusting to get it right.

Step 14: Painting the Skulls!

To paint the 3D printed skulls, we used an airbrush! We started with a beige/sandy base coat, then added some light and medium browns for depth. On the side skulls, the eyes were painted black.

We also painted the jaw bones in the same way.

Step 15: Attaching the Skulls to the Chest!

To attach the painted skulls to the chest, we used....toothpicks! First we marked where they would go with a tiny toothpick hole on the side of the temple area. We then glued toothpicks onto the skull using super glue and a bit of hot glue for added strength. From there, we applied gorilla glue to the ends of the tooth picks and slid them into the foam. This worked surprisingly perfectly!

Once dry, if there were gaps around the skull we carefully filled them with DAP and painted it to match.

The front skull was a little different because it will need to come off occasionally. We accomplished this with magnets! Small magnets were glued into the front of the chest and on the inside of the skull so it can snap on and then easily come back off when necessary.

Step 16: Attaching the Hardware!

Next we attached the hardware! This was done with large thread screws and clear gorilla glue. These are not intended to be ultra strong attachments, they will easily rip out if you grab it and pull. However they are plenty strong for simple usage if you're not too rough.

A little glue was applied to the screws and all the parts were screwed into place.

Step 17: Making the Handles!

Before attaching the lower jaw bones, we needed to make the handles! We did this using the 10mm EVA foam.

First we cut the rectangles, then sandwiched a thick wire on the inside for added rigidity. We glued the two halves together using Barge, and then used the Dremel and sanding drum to shape the edges to look like rough metal. Instead of using Drylok on these, we used a material called Plastidip. Normally this is great to use on EVA foam and its MUCH faster to dry than Drylok, but Plastidip will destroy the pink foam so we couldn't use it on the chest parts.

Once dry, we used Barge to attach a small metal hinge to it. We then applied clear gorilla glue to the back of the hinge, placed them on the sides of the chest, and gently screwed the screws into the foam.

Similarly with the hardware, we painted these with the metallic obsidian acrylic paint.

Step 18: Attaching the Jaws

With the handles and hinges in place, we could close the box and figure out exactly how to position the lower jaws so that it looks like the skulls are biting down on the handles. Once we found the right spot, we attached in the same way we attached the other elements: with the toothpicks and glue method. IT LOOKED SO GOOD!

Step 19: Adding the Fog and LED Effects

With everything else in place, it was FINALLY time for the special effects! First we hot-glued a waterproof LED strip inside the front skull. We wrapped it in a way where you can't see them at all from the front and they make the eyes and cracks glow blue. The LEDs are controlled with an Arduino UNO and a battery pack that got hidden on the inside of the upper part of the chest.

In the front of the chest behind the skull we drilled a small 1/4" hole to fit a hose that connects on the inside of the box to a fancy little device called a Microfogger! This tiny remote controlled device can produce fog and add incredible effects to your props! It's basically a tiny, USB chargeable fog machine that can be controlled with a remote or an Arduino!

Inside the skull we 3D printed a small attachment with three exits for the fog. Two of them point towards the eyes and one points up towards the cracks. This way the fog comes out where we want it to go. This mostly worked pretty well!

All of the electronics then got attached inside the box so they're hidden from view unless you completely open the box up.

With the LED glowing eyes and the fog emitting from the skull, it really makes this look like a CURSED chest!

Step 20: The Results!

Really hope you enjoyed this! It's one of the most complex things we've ever made and we had to explore a lot of new techniques to get it right. We absolutely love Sea of Thieves and we hope we've done the style some justice!

Remember to watch the YouTube video in step one for even more detail.