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)