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)