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)