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)