from cadquery import *

w = 10
d = 10
h = 10

part1 = Workplane().box(2*w,2*d,h)
part2 = Workplane().box(w,d,2*h)
part3 = Workplane().box(w,d,3*h)

assy = (
    Assembly(part1, name='part1',loc=Location(Vector(-w,0,h/2)))
    .add(part2, name='part2',color=Color(0,0,1,0.5))
    .add(part3, name='part3',color=Color("red"))
    .constrain('part1@faces@>Z','part3@faces@<Z','Axis')
    .constrain('part1@faces@>Z','part2@faces@<Z','Axis')
    .constrain('part1@faces@>Y','part3@faces@<Y','Axis')
    .constrain('part1@faces@>Y','part2@faces@<Y','Axis')
    .constrain('part1@vertices@>(-1,-1,1)','part3@vertices@>(-1,-1,-1)','Point')
    .constrain('part1@vertices@>(1,-1,-1)','part2@vertices@>(-1,-1,-1)','Point')
    .solve()
)
show_object(assy)