A droid is made up of many moving parts, but in the case of “Rogue One’s” K-2SO, there were two key components that breathed life into the reprogrammed Imperial security droid turned sardonic Rebel operative.

First was actor Alan Tudyk, the versatile actor who’s embodied roles on a diverse array of films and TV series including “Firefly,” “Suburgatory,” and “Trumbo” (as well as giving voice to a steady string of Disney’s animated characters, including “Frozen’s” Duke of Weselton and “Wreck-It Ralph’s” King Candy). Tudyk provided K-2’s voice and delivered the character’s physical movements on set via motion capture suit, acting opposite co-stars Diego Luna and Felicity Jones.

The second was Industrial Light & Magic animation supervisor Hal Hickel, a veteran of eye-popping film visual effects including “Iron Man,” “Pirates of the Caribbean” and “Pacific Rim." With his team of FX wizards, Hickel finessed Tudyk’s performance into K-2’s digital framework, resulting in the creation of one of the most instantly popular new “Star Wars” characters since the original films.

To mark “Rogue One’s” Blu-Ray debut (available now), Tudyk and Hickel joined CBR at ILM’s San Francisco headquarters to dig into the details of their unique collaboration, which they did willingly – and not because Cassian told them to.

CBR: Alan, as you came up to ILM to experiment and “find” K-2SO physically and vocally, tell me a little bit about that process, and what were the key things that you zeroed in on that you thought were going to make the character work?

Alan Tudyk: When we first started out with the movement and doing the live action where I was standing in the void, where I’m seeing K-2 mimicking my movement, I noticed some subtle movements that had character, emotion – slouching, putting weight on one foot, gave him life really easily. It didn’t take much. And knowing the history of droids in the “Star Wars” universe, I knew that was going to be possible, that he didn’t have to be just some automaton character.

Then it was the script. [director] Gareth [Edwards]and I had these conversations from the beginning: that he’s been reprogrammed, and now he just says whatever he wants. He speaks his own truth, and at times it’s counter to what other people are thinking, or what should be said in a moment, stating the obvious sometimes, or telling people things that he shouldn’t, like, “No one likes you,” which is also more about him.

He’s like a child: “She shouldn’t be here with us” – he doesn’t like her there. “I can’t believe you gave her a gun, and I don’t get one.” It was all of those things that made him really an individual, and different from the other droids that had come before.

Alan comes in sort of in the middle: Hal, you’ve build the character to a degree, then Alan puts a certain kind of life into it, and then you and your team refine that. So tell me about what were the things in his performance that really you leaned into and said, “Let’s make the most of what Alan’s giving us in these different capacities.”

Hal Hickel: We’ve got a system for extracting Alan’s movement, like motion capture people are familiar with, but it’s an on-set version, a portable version of that. But just taking that and applying it to K-2 doesn’t get you all the way there. You’ve got to sort of fit it to K-2’s body, and make sure that it’s communicating all the things that Alan was trying to communicate on set. That’s the animator’s job in this case, is really to preserve what Alan had done, not to change it.

Timing was sacrosanct. We never changed timing. We would push poses, and push the pantomime a little bit to compensate, sometimes, for not being able to see Alan’s face in a particular moment. So that was what the animation crew’s main task was, was to build on that foundation, but preserve it at all times and make sure it was being expressed fully through K-2’s movement.

Alan knew the history the droids in “Star Wars.” How did you apply the lessons from that really rich history, beginning of course with C-3PO and R2, and what’s been done since?

Hickel: The main thing for us was to sort of fit K-2 into the “Star Wars” style book. Gareth and Alan were both very keen from the beginning to see if there were ways to make K-2’s face a little more expressive than just a completely immobile mask, which was really more the usual thing for “Star Wars” droids.

We tried a bunch of different things. In the end, we contained that to being able to rotate the eyes, and have him do those little micro eye movements, which was great. It’s a cool thing, and it conveys thinking, and processing, and all that. We tried eye blinks and everything. We had to rein a lot of that back in order to sort of keep it feeling like something that belongs in the “Star Wars” universe, and in a live action movie. It could very quickly veer into animated film territory, which is a different feeling, a different vibe. So that was the main angle.

Alan, once you got on set in the motion capture suit and the stilts and everything, where did you find your biggest learning curve was in terms of, “This feels really foreign to me, what I’ve got to do,” but then by the end was second nature for you?

Tudyk: I guess the stilts right in the beginning were a little bit challenging. I remember going down a ramp, the ramp of the U-wing. There were two sets of feet. One was these athletic feet that were just fixed on to the post. It was a ski boot, and then an artificial leg, a shin, and a foot. Then there was also another set, which was bionic, in that the toes lifted after every foot fall to make sure I wouldn’t trip over anything. Those were the ones that were meant to go down ramps and things like that.

But I quickly, after a few days, or probably a week or so, I figured out that I don’t need those, and I could not fall while going down ramps. There was just a special way to walk down. That was about it. There were hands that I wore from time to time, when I needed to be very specific in the frame, like punching buttons and things. Those took a little bit to figure out how to be articulate with them, because they were a bit heavy. Whenever I move my hand or move my fingers, those fingers and hands moved.

Hickel: K-2’s arms are longer.

As far as interacting with your fellow actors, when you got a moment to throw in an improv line, because it’s such a technically precise movie, was it always a risk that you’re going to break up your costars with a really good line, and then it’s going to mess it up technically? How did that play out as you were inspired in the moment, in character?

Tudyk: Honestly, I don’t know what it is. I got to a point where I just say the things. I do the lines the way they’re written, and then I pretty much just start talking, I don’t know, and saying things outside. They were pros. They weren’t going to break up – except Diego [Luna] does break up on that one take that’s in the movie where I slap him. You can see his mouth is starting to go up, but he covers his face so you can’t see him laugh.

I wasn’t worried about it. Diego was always poking fun at me, so there was a camaraderie there, making fun of my telescoping head and things like that. He’s a funny guy. And Felicity [Jones] is fantastic. She’s a very generous actress. As a lead character, she was always just one of the other actors.

Hal, did you find that all of the effects team were embracing this character? He clearly became an audience favorite, like early on in the film. Were people like, “I want to work on K-2?”

Hickel: Oh yeah! Animators definitely wanted to do K-2 shots. Yeah, I liked him right from the beginning, right from the first artwork I saw. I think for everybody though, it came to life when we started to hear the voice that Alan was doing, and get the footage back from actual scenes.

I liked him straight off from the beginning, just design-wise. My office is full of toy robots – especially robots. I don’t have like lots of other action figures. I’ve got mostly robots and droids. So I was really into the character right from the start.

What kind of improvisation do you get to exercise when you’re working on the character digitally?

Hickel: Not so much when we’re doing a character like this when we’re partnering with an actor. If we were hand-animating him or something, that would give us those kind of opportunities. In a project like this, our goal really is to, number one, provide Alan with the opportunity to create his performance where it should be created, which is on set with the other actors. Not in isolation on a mo-cap stage at some other time. We do have to put him in this ridiculous outfit with the markings. [to Tudyk] Sorry, it’s silly-looking.

Tudyk: I thought it was cool! Outside of that, there was like a German luge thing.

Hickel: But outside of that, we try not to make it this really super technical experience where we’re slowing down first unit photography and saying, “Hold on, we have to shoot our reference and get our grid.” We try, other than putting him in that outfit, to just let everybody do their thing, and then we do our thing later. Then that way, our job later becomes just preserving what Alan did, and making sure that it’s clearly communicated by K-2 and not messing with it. Especially not messing with the timing, particularly in the humorous bits. We really don’t want to get in there.

Animators love to animate things, so there are some times, particularly early on in a project, where we’re creating a character. You get some folks like really getting in there and doing stuff. “Whoa, whoa, whoa – back off. Let’s just reduce that back to what the essence of the original performance was.” That said, the animators are completely necessary to the process, because it’s not just a technical thing of extracting Alan’s motion, and putting it on the droid, and you’re done. Their bodies are so different that we have to get in and adjust, and make sure that, again, that it’s faithfully transmitting what Alan did.

Directed by Gareth Edwards from a script by Gary Whitta and Chris Weitz, “Rogue One: A Star Wars Story” stars Felicity Jones, Diego Luna, Ben Mendelsohn, Donnie Yen, Mads Mikkelsen, Alan Tudyk, Jiang Wen and Forest Whitaker, is now available on Blu-ray, DVD and Digital HD.