I have not seen anyone make a Rhino costume. I think the reason no one has done it yet is because the character has not been featured in a movie.
If he was a villain in a movie people would be capturing screen shots and trying to replicate the costume. Since it is only in comic form at the moment, he doesn't have a lot of interest.
I would make the costume out of upholstery foam, and latex. So far that is how I make all of my costumes

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Here is an awesome Hulk build thread. I really think you should use the Hulk build as a blue print. It is exactly what you need.
http://www.therpf.com/f24/biopredat...-contest-entry-incredible-164942/#post2560879
Here is a great Venom build.
http://www.therpf.com/f24/giant-style-venom-speed-build-halloween-163222/
Here is a video on how to build a muscle suit.
Incredible Hulk Muscle Suit Costume : BFX - YouTube
You don't have to cover it in panty hoes like they say in the video. Just cover it with liquid latex.
Just make all the muscle groups and attach them to a dummy wearing a body suite.
Stick foam on the body forming the muscle groups.
Add the texture. I burned it in with a wood burning tool. You could cut out balls of foam and stick them to the build for warts.
Next cover the build in latex.
To fill in the gaps between the muscles use cotton balls dipped in latex.
Paint it all in grey, add some black washes, and that should work.
That is how I would do it.