Donaldson made him just for fun.
"Every time I'd go out in public with him," Donaldson says, "I'd get mobbed by people who come running up to me and they say, 'Oh! That's so great! Where can I buy one?'"
But the little robot was too expensive to manufacture. The four motors inside cost $100. To reduce their number took time, hard work and his own clever cam design.
"The original one took about 2 years to build. The second one, the toy, took about 8 years," Donaldson said.
Monkey 2.0 is "Dave." Last holiday season, "Dave" outsold Buzz Lightyear in the United Kingdom, and was the number five top-selling toy. In the US now, he's on the shelves of Toys 'R Us stores.
"Dave" says monkey business is great.
So is life around the household. Nick's two boys are nuts about robots, modifying and programming their own menagerie. Unlike his sons, Nick didn't want to grow up to be a roboteer.
His wife Rebecca kids him about how it all got started.
"For his 30th birthday, I got him a Lego Mindstorms kit. And it just sparked this whole journey," Rebecca Donaldson said. "It's just been sort of to-the-moon from there. So it's all because of me."
Rather than "inventor." Nick considers himself a "maker," part of a new breed of technology buff who collaborate online with open source software, and open source hardware like his Arduino circuit board.
Nick's other robots now compete in national contests. "Ziggy" the spider is undefeated in its class for eight years.
Think of it as the rise of the plan for the apes.