Ethan Hawke has been writing a fan letter to Christian Bale for years - but has never sent it to his acting peer.

The 'First Reformed' star thinks the 'Machinist' actor is ''amazing'' and has kept an email expressing his admiration for his fellow former child actor in his drafts folder for a long time as he doesn't know where to send it.

Speaking to Empire magazine, he said: ''I've written a lot of fan letters in my time. I wanted to write Christian Bale a fan letter, because he and I both started really young and he's just turned into an amazing actor.

''I meant to write it for about three years but I keep keeping it in drafts in the email because I'm not exactly sure how to find him. But he deserves a fan mail letter.''

The 47-year-old actor - who has children Maya, 20, and Levon, 16, with ex-wife Uma Thurman and Clementine, 10, and Indiana, seven, with spouse RYAN SHAWHUGHES - admitted he no longer sits through movies if he's not totally captivated by what's on screen.

He said: ''Truthfully, I think I walk out of a lot of movies. Because I have four kids, I've gotten really impatient. I talked my son into going to see one of those old Italian Spaghetti Westerns. Not the Sergio Leone/Clint Eastwood ones, but some more off-the-radar one. I promised him it was gonna be great. About halfway through he was so unspeakably bored, I was like, 'Do you wanna go?' He was like, 'I really do.' ''

But Ethan doesn't always have a short attention span.

He boasted: ''I've never known anybody with the ability to play with Matchbox cars as long as me.''