I dunno. On the one hand, it would be easier to do than to try and manufacture your own product. On the other hand, it's not too unrealistic to think that LEGO would say "Nah. That's a cool idea, but we're not interested," and then one year later, BAM! LEGO has gone and released their own version of your idea and you don't get to see a single cent. Not that I think LEGO is evil mind you. That just seems to be how companies tend to operate.If I were them, I'd be going to Lego and seeing if they wanted to work something out.
It's a novel idea and probably novel enough application of existing technologies that he could patent it, but there's absolutely no mention anywhere that he has done so. I don't imagine it will be economical for Lego to produce it themselves, but certainly moreso than to license it from a patent-holder. I don't know the patent system for US / Denmark, if it's first to file though then this guy should be worried.
That's the only thing I was thinking that could go bad with that plan. I wish there was a legitimate way of keeping them from doing that, so they could at least have a chance without any danger.