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)