You can find more of Matt Kaufenberg's art here:
http://www.illustrationaday.com/
 
 
You can find more of Steve Lambe's art here:
http://lambebeardo.tumblr.com/
 
 
You can find more of Randy Bishop's art here:
randybishopart.blogspot.com
 
 
One of Luigi Lucarelli's vidoes on character shape sketching. 
More vids and other cool resources here.
You can find more of Luigi Lucarelli's art here:
http://luigil.deviantart.com/
 
 
You can find more of Mateus Santolouco's art here:
http://santolouco.wordpress.com/

And if you understand a little Portuguese, here's a short news spot on his making of the TMNT:
http://www.sbt.com.br/tv/portoalegre/jornaldosbtriograndemanha/?id=a23b20b3fd75bb88a544ef72985ff32b
 
 


Project: Rooftop was probably the first place dedicated to posting redesigns of (usually) famous characters I found, and it's thanks to it that I've come to know the works of so many artists with such different and varied styles and approaches, which has taught me a lot about both art and character design, besides all the fun of looking at so many pretty pictures. :-)

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Miss America by Lar deSouza.
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Clayface by Bernales and Turcotte.
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Legion of Substitute Heroes by George Kambadais
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Donnatello by Kris Anka
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Magik by Ronnie del Carmen
 
 
You can find more of Darren Rawlings' work here:
http://www.thinkmorestudios.com/
 
 
You can find more of Ross Campbell's art here:
http://www.greenoblivion.com/
 
 
You can find more of Andy MacDonald's work here:
andymech.blogspot.com
 
 
You can find more of Kris Anka's work here:
http://kristaferanka.tumblr.com/