What puts together composites according to Buddhism? I believe that the word for composite or compounded dharma is sankhara. What puts sankhara together, according to Theravada or Mahayana Buddhism?

I'd especially like an explanation that contrasts the answer to Hinduism.
The word 'sankhara' has many different meanings. It can mean:


"conditioned thing' (something made from causes &amp; conditions; AN 3.134; Dhp 277; SN 22.90)
"conditioner' (a condition that conditions/creates another conditioned thing; SN 41.6; MN 44).
"conditioning" (the process of conditioning; SN 22.79)
aggregate of mental formations (sankhara khandha; SN 22.79; SN 22.48)
mental conditioning (i.e., mental proliferation, psychobabble or papanca; Dhp 203; SN 38.14).


Therefore what puts together a conditioned thing (sankhara; sankhata) is the conditioning (saṅkharonti) of other conditioned things (sankhara). 

In the context of mental formations (sankhara khandha), SN 22.79 says:


  Kiñca, bhikkhave, saṅkhāre [plural] vadetha?
  
  And why do you call them 'fabrications'?
  
  Saṅkhatamabhisaṅkharontīti kho, bhikkhave, tasmā ‘saṅkhārā’ti vuccati.
  
  Because they fabricate [saṅkharontī; verb] fabricated things
  [saṅkhatam], thus they are called 'fabrications'[saṅkhārā]
  
  Kiñca saṅkhatamabhisaṅkharonti?
  
  What do they fabricate [saṅkharonti] as fabricated thing [saṅkhatam]? 
  
  Rūpaṃ rūpattāya saṅkhatamabhisaṅkharonti, vedanaṃ vedanattāya
  saṅkhatamabhisaṅkharonti, saññaṃ saññattāya saṅkhatamabhisaṅkharonti,
  saṅkhāre saṅkhārattāya saṅkhatamabhisaṅkharonti, viññāṇaṃ viññāṇattāya
  saṅkhatamabhisaṅkharonti.
  
  For the sake of form-ness, they fabricate form as a fabricated thing.
  For the sake of feeling-ness, they fabricate feeling as a fabricated
  thing. For the sake of perception-hood... For the sake of
  fabrication-hood... For the sake of consciousness-hood, they fabricate
  consciousness as a fabricated thing.
  
  Saṅkhatamabhisaṅkharontīti kho, bhikkhave, tasmā ‘saṅkhārā’ti vuccati.
  
  Because they fabricate fabricated things, they are called
  fabrications.


In the context of intentional kamma (action), AN 3.23 says:


  A certain person makes/generates/puts together
  (abhisaṅkharoti) hurtful (sabyābajjhaṃ) body
  choices/intentions/activities (kaya-sankhara), speech
  choices/intentions/activities (vaci-sankhara) and mental
  choices/intentions/activities (mano-sankhara).
  
  Saṅkhāra Sutta