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)