Rocket's Detonator From Guardians of the Galaxy Vol. 2

There are some minor spoilers here, so if you haven’t seen Guardians of the Galaxy Vol. 2 yet, you should probably go see the movie and then come back before you continue with this instructable.

Like a lot of movies lately, GotGV2 has a problem that would best be solved with high explosives. Unfortunately for our heroes and heroines, while they have a detonator, they lack the necessary explosives. That is until the trash panda remembers he decided to teach an alien race a lesson in humility by stealing several of their very valuable and extremely explosive Anulax batteries (those with sensitive nipples may know them as Harbulary batteries). Add a few feet of wire to lash a couple of the batteries to the detonator, and we have a bomb that should do the trick.

Watch the trailer here: Guardians of the Galaxy Vol. 2 Teaser Trailer by Marvel Entertainment.

I wasn't able to complete the entire build, so consider this Vol. 1 of 2. Vol. 2 will be out soon and will cover the addition of the Anulax batteries and the other cosmetic, non-functional features. The batteries are close to complete, however the "bulb" parts are proving to be rather difficult to build. I'll get them though!

Check out the photo and video of the work-in-progress, as well an image of what the final product will look like, minus some parts that are just decorative or are very difficult to model.

Anyway, let's get started!

Step 1: Step 1 – R & D

The process of creating something usually has 2 phases, the research and design phase, and the build phase. Almost everyone has a favorite phase, and mine is definitely the design phase. Don’t get me wrong, I really like building things, but there’s just something about the design phase that I love. Maybe it’s the constant problems that need solving? Since most of what I make is digitally manufactured, maybe it’s the anticipation of seeing something on the screen and knowing it will be a real, physical object soon? Regardless of why, for this instructable the R&D is done for you, but I’ll run through the process to give you an idea of how I go about re-creating something that already exists, like a film or television prop.

The first step in replicating a prop is locating as much reference material as you can. Sometimes you’ll find detailed drawings or clear photographs with some something for a size reference. Other times, as was the case here, you only have a few images from the footage to work from.

A couple particularly helpful websites are ScreenUsed and Prop Store. Both specialize in selling and auctioning screen-used and other types of film memorabilia. They often have photos with rulers for scale, along with other extremely helpful information. Be careful though, looking through their archives can make your to-do list get much longer!

Another great resource is TheRPF.com also known as The Replica Prop Forum. TheRPF is an online community with thousands of members that can help with all aspects of re-creating a prop or costume.

The next step I like to take is to define a master view to relate all measurements to and from. For example, I was able to find a shot that was mostly looking straight down onto the top of this device. However, it was not quite straight down and this caused some distortion. To correct this, you can use photoshop to remove the perspective. It is really only reliable for a single plane in your image, but often that’s all you need. Here is a good description of this process: Keystoning

Once you have a good starting image, you need to define a scale. Sometimes this is easy, like if you know the prop is 12 inches long. Othertimes you have to make your best guess and go with it. There is also another situation, which was the case with this prop: It has a component that is a real world object, the 7-segment LED clock. After taking a quick look through Digikey’s online part catalog, I found what I believe to be the best version of the LED clock, and it is listed as being 2.016” by 0.752” in size. After tracing the profile of the clock, I scaled it to be 2.016” wide, and the height came out to 0.767” which is close enough for me!

After you have the scale down, it’s just a matter of generating all the geometry for your project. I find it’s helpful to take a guess at the appropriate size and then compare it to your reference, then adjust accordingly. It can also help to use perspective in your 3D modeling software, as the lack of perspective can make things seem to be a different size or at a different angle than they really are.

I looked at dozens, if not hundreds of switches to try to match the two switches seen on the film prop. Some were close, but I didn't find any that were close enough for me, so I decided to make them from scratch. The easiest way to do this is to use existing parts and build the custom parts to work with the off-the-shelf parts. You can see how I've done that with both switch types in the exploded views shown in the next step.

And that’s it for the Research and Development portion of this instructable. Each project will be different and come with its own set of challenges, but that’s part of the fun!

Step 2: Make It Real

So now that you have your creation in digital form, it’s time to bring in into the real world. There are several different ways to do this, including: · 3D printing · Laser cutting and/or engraving · CNC machining · Hand or power tools · Sculpting · Thermoforming / vacuforming / blow molding And many different materials to work with, like: · ABS, PLA or other plastics or resins · Wood, cardboard, Acrylic or other plastics · MDF, Plywood, machinable wax · Foam, aluminum foil, clay Each material has benefits and drawbacks that determine which is the best to use for a particular project. Most of the time you’ll use several of each of the techniques and materials. I’m lucky enough to own a Form2 SLA printer from formlabs. It can produce parts with a ready to use finish with almost unbelievable detail. It’s perfect for projects like this, where (as you’ll see in a moment) some of the parts are small and intricate. I’ll be 3D printing everything, except for the clear bulbs around the batteries (those will be vacuformed around a 3D printed form, or cast in a silicone mold made from a 3d printed part) and the bits that are real-world objects, like the LED clock, wires, rods etc. I will also use a laser cutter to make the box, since it’s a relatively large part and is expensive and time consuming to 3D print. I guess now is a good time to go over the parts of this prop. Check out the images for exploded views of the detailed parts.

Step 3: 3D Print Components

This detonator is a fairly small part, and because it was necessary to custom make the moving components, a high resolution 3D printer is the ideal tool for the intricate components.

My printer is a Form 2, and it is fantastic.

The images shown in this step are of my printing station, as well as the printed components, except for the lid.

As you'll see in the next step, I originally intended to make the entire enclosure from laser cut wood. However, that plan included only the use of the buttons, not the levers as well. Later on I decided to make this device more screen accurate, and this dictated the top be high precision to accept the levers and their concealed switches.

You can see the support material still attached to the parts. The Form2 software can automatically calculate the support locations, but it isn't perfect and some designs print better with a human determining where support is needed

Step 4: Laser Cut Box Components

To save resin on my printer, I decided to laser cut the enclosure parts from 1/8th inch craft plywood. My local FabLab has a laser cutter, but I tend to not use it because it's about an hour round trip of driving.

I ultimately decided to print the lid because I needed the precision for the lever switches, but this step will show the process of making the entire enclosure.

The first thing you need to do is to turn your 3D model into a 2D drawing. This lid is well suited to this process, as it is layered 2D shapes to make a 3D object. Simply export a view of your part, then separate each layer onto its own drawing. Then cut them out of the appropriate thickness material. In this case there are some small detail parts in the corners, and the bottom layer is intentionally misaligned. In order to make it easier to line everything up, I engraved some alignment outlines into the appropriate parts. This made it much easier to align everything later for gluing.

I used a combination of wood glue and hot glue to put the box together. The lid was laminated with wood glue, and the box was assembled mostly with hot glue. Anywhere parts are butted against one another, I typically use hot glue. Anywhere the parts are laying surface to surface against one another I use wood glue.

Once everything was glued up and dried, I sanded the “ramp” parts of the box to a point where they tapered down into the rest of the box. I used my stationary belt sander for this and it was pretty straight forward. I then used a file and sandpaper to round over the corners.

Next came the primer. I really like the Dupli-Color high-build filler primer. It leaves a nice smooth finish and does a great job filling in grain, 3D print lines, and scratches.

After the primer cured, I sanded all the surfaces to an even surface. Anywhere there were low spots, I applied spot putty. After letting that cure, I sanded it all even and then applied a final coat of primer.

Step 5: Assembly

About this point I decided to make the lever switches functional. Doing this required the lid to be modified. I tried to make the modifications with my Dremel, but wasn't successful. I decided to re-make the lid as a 3D print, and to incorporate part of the lever switch in the lid.

Once I had the new printed lid in hand, I primed it to match the box from the last step. I also needed to mask of the inside of the switch holes. I used a technique that worked really well. For the lever switches, I used hot glue to fill in all the complex geometry withougt leaving any masking on the top. Just a little isopropyl alcohol causes the hot glue bond to fail and the "plugs" come out easily, leaving a pristine surface behind.

For the pushbuttons, I used some earlier button pieces as "shields" to prevent primer from getting on inside surfaces.

Next it was time to install the buttons. To accomplish this I simply placed the parts in their final locations and used hot glue to hold them in place.

You may notice in some images there is ribbon cable running to the LED display. I later removed this in favor of extending the legs on the LED display, seen in the next step.

Step 6: Electronics

This was easily the most frustrating part of this build. Except maybe the bulbs on the Anulax batteries. I didn't bother to model the electronics thinking that there was sure to be enough room to include them all. Turns out, this thing is considerably smaller than I expected, even though I designed it.

I was able to get everything but the battery in, and the battery is connected via a connector routed through a hole in the side. I may rework this in the future to get the clearance needed for a battery to be installed in the unit.

You can see one of my other favorite techniques for hot glue. I used quite a bit of it here to locate parts and secure wires. The ease of removal using isopropyl alcohol makes it great for this use.

The controller is an Arduino Pro Micro, and the LED display is from Adafruit and includes an I2C backpack which allows the LED display to be controlled with just 2 additional pins instead of the 12 it would require to control the 7-segment display directly from the Arduino.

Take a look at the schematic to get a better idea of what is going on here.

I've also added a text file of the code the Arduino is running to make this work. I'm far from a programmer, but this works reasonably well. At some point I want to add a reset button, or code in some way of stopping the countdown. As it stands, once the countdown has started, the only way to stop it is to remove the power source.

Step 7: Remaining Steps

So, that was how I built the functional pieces for a replica of Rocket Raccoon's Detonator from Guardians of the Galaxy Vol. 2.

It's far from complete. I still need to:

Add the decorative wires

Figure out the bulbs for the Anulax batteries (I'm thinking vacuform around a collapseable form, I'll try it this week)

Add the tape and wires that holds the lid on

Add the screen and greeblies to the LED display

Give it a good weathering

But I think it's a great start. I really hope you enjoyed seeing my process for creating this prop, and I hope you'll check back in a couple weeks to see the final result. Please, ask as many questions as you can, and thanks for looking!