I think if you're going to be using his idea, it's bad taste to use him as the designer and only give him a few %. If you're going to copy his idea, which you'v

I think if you're going to be using his idea, it's bad taste to use him as the designer and only give him a few %. If you're going to copy his idea, which you've said he's already started bringing into reality, then offer nothing and prepare to potentially lose a friend over 'some residual income.'