Okay I am almost there grin , tnx so far, but its now always draws an square-like cube, but I want to allow a rectangle-like cube too. How to change this? Here is the code by the way but an example will do to (please note that vec is the position the cube is in the map):

Code:
vec_lerp(vec, vMin, vMax, 0.5);
draw_point3d(vec, COLOR_RED, 100, 50);

vec_sub(vMin, vec);
vec_sub(vMax, vec);
vec_rotate(vMin, vector(camera.pan, 0, 0));
vec_rotate(vMax, vector(camera.pan, 0, 0));

//bottom
draw_line3d(vector(vec.x + vMax.x, vec.y + vMax.y, vec.z + vMin.z),NULL,100);  
draw_line3d(vector(vec.x + -vMax.y, vec.y + vMax.x, vec.z + vMin.z),drawcolor_vec,100);
draw_line3d(vector(vec.x + -vMax.x, vec.y + -vMax.y, vec.z + vMin.z - k),drawcolor_vec,100); 
draw_line3d(vector(vec.x + vMax.y, vec.y + -vMax.x, vec.z + vMin.z),drawcolor_vec,100); 
draw_line3d(vector(vec.x + vMax.x, vec.y + vMax.y, vec.z + vMin.z),drawcolor_vec,100);
//top
draw_line3d(vector(vec.x + vMax.x, vec.y + vMax.y, vec.z + vMax.z),drawcolor_vec,100);
draw_line3d(vector(vec.x + -vMax.y, vec.y + vMax.x, vec.z + vMax.z),drawcolor_vec,100);
draw_line3d(vector(vec.x + -vMax.x, vec.y + -vMax.y, vec.z + vMax.z),drawcolor_vec,100); 
draw_line3d(vector(vec.x + vMax.y, vec.y + -vMax.x, vec.z + vMax.z),drawcolor_vec,100); 
draw_line3d(vector(vec.x + vMax.x, vec.y + vMax.y, vec.z + vMax.z),drawcolor_vec,100);
//other lines
draw_line3d(vector(vec.x + -vMax.y, vec.y + vMax.x, vec.z + vMin.z),NULL,100);  
draw_line3d(vector(vec.x + -vMax.y, vec.y + vMax.x, vec.z + vMax.z),drawcolor_vec,100);
draw_line3d(vector(vec.x + -vMax.x, vec.y + -vMax.y, vec.z + vMin.z),NULL,100);  
draw_line3d(vector(vec.x + -vMax.x, vec.y + -vMax.y, vec.z + vMax.z),drawcolor_vec,100);
draw_line3d(vector(vec.x + vMax.y, vec.y + -vMax.x, vec.z + vMin.z),NULL,100);  
draw_line3d(vector(vec.x + vMax.y, vec.y + -vMax.x, vec.z + vMax.z),drawcolor_vec,100);