upsides to making a portal to heaven  
    to   build   the  factory   there   
  
                                          
 first of  all,  real estate:  the highly 
 fractalized  geometry  (not  proven  but 
 likely to be  the  case)  implies almost 
 unlimited room;  even if the portal tech 
 would  be  stolen,  chances  of  running 
 into a  competitor  is  close  to  none, 
                                          
 secondly,  the  resources:  heavens  own 
 alchemical   properties  (proof  exist!) 
 makes  most  base  materials  easily and 
 readily  available.  once  the molecular 
 movement  patterns are mapped  out,  any 
 compound   can   be   created  virtually 
 without                            cost. 
                                          
                                          
  
   downsides  to  making a portal  to   
  heaven  to  build the  factory there  
  
                                          
 current  portal tech  takes some  energy 
 to hold open, which  isn't  a problem in 
 itself.  test results however has  shown 
 that without an active tether,  heaven's 
 time flow breaks  down completely.  even 
 a momentary  fluctuation of  the  portal 
 would   render    all   remote    assets 
 practically  lost.  much  care  must  be 
 taken   to  maintain  portal  stability. 
 (one  option could  be  several portals)