How to build 2 kinds of lego guns into custom

If you have seen Nate's blog about custom Legos, It may not show how you make custom Legos, for sure I don't now how you build custom Legos either! I know these 2 kind of gun you can make into custom. 1. Find a Lego gun, then use tape or this custom scope, (If you have one.) Then find a Lego knife and put it on your gun! hope you enjoy reading this!