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)