You can construct all this without any drawing anything! ;)
Just use helpers lines and the Line function !
Call Line function but draw only helper lines !
AB (center of each circle)
MM' (diameter perpendicular AB)
NN'
MN' (N' is hidden by the dialog box on this image :)
M'N
J is the intersection of MN' & M'N
JB then Reorient it ! (Rotate from J toward N - will be the same toward N' for another internal tangent)
Tangent Click first point
Tan / Tan on the circle = Click second Point
et voilà ;)
Seems the more easy for the moment before Michael makes a special script :D
Moi is fabulous for any 2D geometry's construction! (surelly the same in 3D ;)
here the image ;)