I really like the 1st and 4th one, alongside with the Meta Ridley I posted....I wish they were real...
1st one IS real, it consists of a bit customized painted parts of already existing LEGO and Bionicle sets. Ridley can be made by using Kre-O Ripclaw`s (another robot dragon that can transform into a more human-like robot, but with wings, claws and a tail) parts and few LEGO things and he will look pretty close to him. The only thing left would be recolor him in purple.
Kre-O Ripclaw`s dragon mode:
He would need different feet, a bit modified head and a different tip of the tail. And recoloring of course.
You know what...looking at the last 2 and 1st image, i wish there was a LEGO Nintendo game with Ridley being a playable character, like Reptile in LEGO Marvel Super Heroes...but that is a dream that will most likely never be real.
And i found this custom figures (one of them can be bought right now on eBay/could be bought, but was sold already):
Oh, man, why there is no official Ridley figure? Like those S.H Monster Arts Godzilla figures.