Hi @birthday-cake-rockz! I hope its okay if I answer your questions here in a separate post. I definitely have some tips and thoughts for help with drawing Raph.
First of all, I recommend This free PDF of the book "Morpho - Fat and Skin Folds: Anatomy for Artist" for those who are interested in really getting familiar & comfortable with drawing larger/fat/thick body types. (Make sure you click the second link, the first one is broken)
Now for Raph specifically, I do have a one very important shape I use when I draw him that might be helpful:
A lot of people like to associate diamonds with Raph as much as squares, and I think that's accurate to his design, too! The boy has a lot of serious neck muscle going on, and so his trapezius muscles and those surround it are gonna be more visible. Which actually creates a diamond shape around his collarbone and upper body. If you follow along with the angles of his shell, you can create this shape to help give him that stronger upper body look!
As for his leg proportions, that's a bit tricky because unlike his brothers, Raph's lower limbs are disproportionate to his upper limbs. It's a case of "you have to understand the rules of anatomy in order to break them".
SO!! Real quick anatomy lesson that I learned in art school: the average adult body should be about 7 heads high. Because the boys are teenagers, theirs come up to be about 6 heads high, which I credit to their younger age. But as you can see by the red marked areas, everything is still in normal proportion.
Raph, on the other hand, is different.
Raph's arms are as long as his body is, and his legs are much shorter than his arms. Because of this, he's actually disproportionate to his brothers, since his height is only about 5 and a half heads tall, rather than 6 or 7. In particular, his thighs seem to be unequally shorter in length than the calves. I think its important to keep that in mind when draw him! Because even if you know he's made up of all these thick, blocky shapes, if you try to give him the normal proportions you would Leo or Donnie or Mikey, it might still not look right. He's a stocky lad, and his upper body strength is showcased by these design choices.
Hope all this was helpful for you guys. Now go be free and draw him to your hearts content! :)
Additionally, here are several other links to posts people have created that give references of Raph and the other turtles! I'm sure these will be a big help, too.
High Quality Reference Sheets of everyone, including April and Splinter
Turtle Side Profiles Specifically
MASTERPOSTS by @melancholic-rowen: RAPH | LEO | DONNIE | MIKEY | APRIL | CASEY | CASEY JUNIOR
