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)