Duncan Jones, director

I wanted Sam Rockwell to play the villain in Mute, a film I later made for Netflix. But he wanted to play a blue-collar kind of guy. We both liked the sci-fi films of the 70s and early 80s – Silent Running, Alien, Outland – and the sense of realism and mundanity they brought to space, with a lot of the day-to-day grind comparable to jobs on Earth. So I said: “Let me see if I can write something.”

I developed the story, about a man mining helium-3 on the moon who meets his clone – and Nathan Parker wrote the script. The moon base is called Sarang, the Korean word for love, because I was in a long-distance relationship with a Korean girl at the time. The frustration and sense of isolation that Sam Bell, the main character, feels is definitely something I was channelling. I also thought there was something interesting about having the opportunity to meet yourself from a different point in your life, to see how a mature version of yourself would interact with a rawer, more emotional one. That’s certainly how I’ve changed in the course of getting older.

My flatmate Gavin Rothery did a lot of the concept art. He gave the moon base and Gerty, the robot voiced by Kevin Spacey, their look. While we were working on it in London, we ordered so much food from Mexicali on Fulham Road that we ended up using their takeaway boxes for Sam’s space rations. We built the moon base as a full 360-degree set and we would seal the cast and crew in at the start of the day. That set gave us confidence, though it cost close to a third of our $5m (£3.9m) budget. It’s hard enough to make a low-budget movie without fretting about: “Oh, I can’t pan here because I don’t have enough set.”

We wanted to make stuff seem as real as possible. A lot of love and attention was put into the miniature vehicle models, but they needed extra visual effects, such as dust kicking up off the tyres. Then there was the problem of the interaction between the two Sams.

Nowadays, that kind of multiple performance, achieved with CGI, is quite common, but it was much harder in the noughties. We picked scenes that would give the most impressive visuals featuring both clones so the audience never felt cheated. For the fight scene, Sam wrestled with a stunt guy who was wearing a green stocking over his head and we swapped it out digitally later.

I don’t think Moon was negative about technology but it wasn’t particularly positive either. Right now, I’m desperately hungry for more optimistic sci-fi because we bloody well need it. How does mankind get itself out of this predicament? Can we see a future we can get excited about? Moon was 10 years ago and it’s crazy how much the world has changed.

Sam Rockwell, actor

There’s a part of every actor that wants to control every scene, so when you’re playing both parts you have that. But Moon was still daunting: a brainfuck, for sure. To differentiate the clones, I started improvising with an actor friend, Yul Vazquez, and Duncan would film us. I had been listening to Jeremy Irons’ DVD commentary on Dead Ringers, in which he played twins, and he talked about contrasting energies. That’s what we did: an alpha/beta thing. One clone had been there alone for three years, so he was a bit Robinson Crusoe, a bit batty. The other was full of testosterone.

Duncan incorporated all this into the script but he was still concerned the audience wouldn’t know who was who. There was a whole conversation about using a wig and it was not a great wig. I said: “I really don’t think we should do that.” It would have not worked for the whole movie. I pushed for using wardrobe and makeup to subtly distinguish them. We did snug clothing and healthy makeup for the healthy clone, baggier clothing for the other. I used props, such as reading glasses and hats, and stole Ratso Rizzo’s cough from Midnight Cowboy for the sick clone.

A lot of the time, I was acting opposite a tennis ball on a stand, or opposite Robin Chalk, an actor who looked like me from the back. I would go into makeup to switch to the other clone two or three times a day – we were trying to complete whole scenes. It was a wild experience. There was a writers’ strike, so we were basically alone at Shepperton Studios. I was very monk-like during that period, just going to the gym and eating chicken, rolling cigarettes and drinking coffee.

It’s a milestone in my career – it’s been celebrated in this underground way. It helped promote a resurgence in intellectual sci-fi, such as District 9 and Ex Machina. Who knew the movie would have this life?

• Moon is out now on 4K Blu-ray.