TOY INVENTION SUCCESS STORIES?

Hi ALL !
The toy industry is unique in that is depends on a huge community of outside inventors and designers for new concepts. Can anyone share any success stories you may have had with selling/licensing a concept to a toy manufacturer? How about bad deals/failures?

How did you negotioate it - for a flat fee, per-unit percentage?

Hi,
Companies are always hesitant to go with a high initial investment if it is your first collaboration.
So I always negotiate towards a royalty-payment (good for the long term!) with a reduced hourly fee.
It makes things very attractive for both parties and ensures professionalism.