"Nobody was more surprised than me," May said of its popularity.
"It was an idea that had kicked around for the best part of a decade ... pictures of things beautifully laid out made us think about it again. We thought we'd just put them together and talk about it - it would be quite a good joke if we can get away with it."
He explained they did "get away with it" and a second series of the programme was made, with a third possible.
"Looking at the feedback - I'm thinking more the social media feedback and the down the pub type feedback - there are older people - I'm talking my age and older still, mainly blokes, let's be honest, who come from a background of making do and mending.
"The weird thing is it also seems to be quite popular with people sort of student age who, to be brutally honest, told me what they like to do was come home from the end of a night out, put on The Reassembler with James May, get slightly stoned, and watch it.
"It's a sort of cult high programme for bong enthusiasts.
"That's fine. I don't mind - if they get off on it that's tremendous. Keeps them off the streets!"
May explained his fellow Top Gear presenter Richard Hammond - who was involved in a shocking crash recently - was on the mend.
"Hammond is ok. He's stumping around on sticks. He's quite bad-tempered I suppose, but he would be. He's going to get better. It's going to take several weeks ... [but] several weeks of an unbearable Hammond stumping around being bad-tempered [is] a small price to pay for his survival and presence."
As for his well-known complaint about his (now sold) Rolls Royce causing him to itch, May said all the rumours were true.
"That's genuine. Never got to the bottom of it. It's not leather ... but it's something about leather when it gets old. It does make me feel a bit weird. It sounds a terribly first-world problem, this: 'I can't drive my Rolls Royce anymore it makes me feel a bit off'.
"It's pathetic, but it did. All that stuff about me having to boil my clothes and have a shower. It's all true."
