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)