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)