Electric Cross Bow

diy
http://blog.modernmechanix.com/build-a-hunters-crossbow/

https://www.medievalcrossbow.info

https://crossbow.wikia.com/wiki/Steel_as_bow_material

https://crossbow.wikia.com/wiki/Bow_design

https://crossbow.wikia.com/wiki/Glassfiber_as_bow_material

3
http://www.google.co.za/search?sourceid=chrome&ie=UTF-8&q=electric+crossbow+youtugbe

http://www.youtube.com/watch?v=BSjCY2kGyfI

http://www.youtube.com/watch?v=0R9u2gjbw1w&feature=related

http://www.youtube.com/watch?v=xLMd_B5bJU8&feature=related

http://www.youtube.com/watch?v=0R9u2gjbw1w&feature=related Note design, can automate using electric pulley

http://www.youtube.com/watch?v=4DaD_HGBoWw&feature=related home made repeating cross bow

http://www.youtube.com/watch?v=Yrv3nmOcv5M&feature=related home made bolt actions with 3D cad files and three step video tutorial on building it.

compound bow build
https://www.youtube.com/watch?v=CxFIdRoqaFA scratch built compound bow

slingbow
https://www.youtube.com/watch?v=KRCD0r58Sqs

steel ball
http://shoottech.com/Page/Web/AR480MARKII