Name of Add-on: Poly Weld
Size: SVN - dynamic size
Description: Epic weld that makes the props be like one prop and isn't laggy like other welds =D
URL: http://gmod-haza.googlecode.com/svn/trunk/gm_queryphys/garrysmod/
Sever of Installation: Wire Build

ADD EEEET =D

Parent tool does the exact same thing, what tomcat said learn to use it. fyi don't parent tool before smart constraint.

Parent tool removes the physics of the object while Poly Perma Weld, combines the two physics meshes together creating one single model. Do not smart constraint your parents, get a wire chip or something relatively and place it in or on your contraption. Then no collide the props you want to parent to the wire chip and then parent. This saves server lag and number of constraints.