Book about some teenagers building a robot

Question

I’m looking for a young adult book I read around the mid 2000s. I was living in Bahrain at the time, but the book was in English and I think it was bought in England (Manchester). I think the book had a purple color and ~250 pages. It was about some teenagers winning some sort of science competition to work at this world famous lab where they all had their own projects and had whatever materials they needed provided by the company.

The main story is about a pair (boy and girl, I think around early teens) that built tiny robot with true AI. The story starts going downhill when other teenagers go missing when they don’t show enough progress. The world famous scientist (?) that’s running the whole program turns out to be evil.

Answer 1

The Inventors by Alexander Gordon Smith and Jamie Webb looks like a match: published 2007, 385 pages.

Description from amazon.co.uk:

'We're about to spend a year with Ebenezer Saint, in Saint Solutions and we've got a free reign (sic) to make just about anything we dream of. This is heaven, Nate, heaven.'

Nate and Cat absolutely love inventing. You name it, they've tried to build it. After accidentally turning their headmaster blue, they win a year's scholarship with the world's richest, cleverest, most charismatic inventor, Ebenezer Saint. And along with twenty-three of the brightest scientific minds in the land, they begin their year-long stay in the Saint's Solutions paradise, a vast industrial compound filled with unimaginable inventions.

But it soon becomes clear that all is not what it seems. Ebenezer Saint is hiding a dark agenda - and if Nate and Cat ever want to see their families again, they will have to out-wit, out-run and out-invent the world's greatest inventor..

One of the reviews there mentions a tiny robot Clint.