Mech Modular NG3

This is a modified version of Kmech_toys's model Mech Modular NG3. Modifications:Refined the original model which has many non manifold edges.Enhance the strength of joint dock at the bottom of body part.Decrease the size of joint ball with 96.5%. The original joint ball is too tight to break the model.Tested on bamboo X1 with bamboo studio use different slice options.