What’s the best way to impersonate someone who might become the next President of the United States? Philippe Reines, one of Hillary Clinton’s longtime confidants, took on the job of playing the Donald Trump during Clinton’s debate prep sessions, pulling off the kind of method acting that would give Daniel Day-Lewis a run for his money.

According to Politico, who interviewed Reines for the first time since the campaign’s conclusion, preparations were so secret that Reines kept his costume in a case that he handcuffed to his wrist whenever he traveled to meet with Clinton before the debates.

Reines purchased four podiums on Amazon, two for his home and two for the secret office the Clinton campaign lent him at the Perkins Coie law firm in Washington, D.C. He searched eBay for a 2005 Donald J. Trump signature collection watch, which he purchased for $175. He experimented with a self-tanning lotion on his face. Before prep sessions, Reines began suiting up with velcro knee pads (to keep his legs straight), a posture enhancer (to keep his arms back), and dress shoes with three-inch lifts (to match Trump’s 6’1 frame). His longtime tailor fit him for a loose-fitting suit with large cuffs. His goal was not a Saturday Night Live-style caricature of Trump, so he didn’t try to replicate Trump’s famous mane. But he wanted to approximate his physicality so that Clinton would grow accustomed to Trump’s looming presence when she saw Reines in her peripheral vision.

While preparing his impersonations, Reines studied Trump’s behavior during previous debates, memorizing physical and conversational idiosyncrasies and tics, trying to learn how to anticipate what the GOP candidate would say next. “He’s one of the most predictable unpredictable people,” he told Politico.

Reines now takes “great pride” in being able to predict Trump’s behavior, like blaming his defective microphone during a debate prep session before the debate in which Trump actually did claim his microphone wasn’t working, but also says it’s a little worrying sometimes when he can’t quite tell where he ends and his Trump persona begins: “There are times when he says something and I spend five minutes trying to figure out if I was copying him or if he was copying me.”

The full report from Politico is worth a read. One of the Trump characteristics Reines identifies is a compulsive need to strike back: “When you kick him in the shins, he kicks back. There’s no such thing as being the bigger person.”

On cue, the president-elect provided a real-time example, by lashing out at Rep. John Lewis, a civil rights icon who testified against Jeff Sessions, Trump’s nominee for attorney general, and described Trump as an illegitimate president. Here’s how Trump started off Martin Luther King, Jr. Day weekend, by attacking one of King’s colleagues in the movement.