I'm trying to hard-code my mob's model, but it takes a lot longer because I'd always have to reopen my client whenever I change something in its code to update. I used the Debug client feature, but it only works with certain things, (not limited to) such as removing/adding new AI. The thing I need help with here, is how to modify my mob's model with a debug-like feature, without having to reopen Minecraft every time I'd want to refresh/update.

You could use the techne-modeller (http://techne.zeux.me/) to model your mob/something (it has a nice workflow) and export that to .java file which is the model.

Techne is a good program for modeling, but my computer doesn't like it.

So how did you model without techne?

http://www.mfmesi.ru/uploads/maxed/fmcmodeler/

Old, but good.

You could use the techne-modeller (http://techne.zeux.me/) to model your mob/something (it has a nice workflow) and export that to .java file which is the model.

except that the .java file spit out by techne is really messy and sometimes just wrong.

I would try to use an obj model.

But don't blame me if it doesn't work, i never tried to create a mob.

I should have phrased it a little differently, I already have the model done and ready to use. I'm adding its diff child parts and it can be pretty difficult not knowing how the model might end up. The debug client doesn't seem to update with the code, which is why I always have to reopen Minecraft every time I change something in the code (mainly child position/rotation).