Ground on Outlet w/ Minimal or No Wall Damage
	
	
		Hello,
I have two prong outlets in my home (built around 1946).  I have two outlets in the bedroom that need to be grounded.  I have grounded a few other outlets in the house by running wire to a cold water pipe and a ground rod I installed.  When I grounding those outlets, I ended up with quite a bit of plaster repair.  Is there a way / and or a tool I can use to minimize or eliminate wall repair?  Once I drill a hole in the sole plate (via my crawl space access), I will have unimpeded access to the electrical box.  
Thank you.