Make Human Models are Ok ... But I will be retopologizing all for the finished model. They will only contain a simple bone structure, as Sandbox only seems to respond to a small set of animations (look in the wiki) Hip,thigh,shin,foot,toe ... abdomen,chest,neck,head...., arm, forarm, hand. I will not be delving into finger and facial animation, as this requires much more collaboration (lip syncing) and full hands are a waste of texture space and veriticies . The model will be divided into seperate objects like ......
..... so that most of the bodypart objects can be assigned to a single bone to make rigging easier. Also considering clothing and Equipment, simple shapes can/should be added around the Joints, as to overlap the bodypart objects at the Joints, think Knee-pads and Elbow guards. Remember Halo, and Unreal Tournament ...
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Also, for Better quality textures, I can map one leg and one arm, then duplicate for the final model, This will leave more space for detail in the texture, but you must avoid Lettering and
Symbols on the Arms and Legs as it will be flipped on the duplicate. Also you must understand that I'm quite new to Sandbox, and the Md2 format. I'm not sure, but I believe if you want weapons, they will be easier to incorporate into the model, rather than add them as seperate object, because of the Md2 format. Here is an example of a tester I was playing with ....