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)