Homebrew PCBs

You guys probably already know this.  But I got a real kick out of 
this - when it worked the first time I tried it.

I have discovered one neat trick with Eagle.  It is trivial to get a 
beautiful "ground plane" around all your traces. While still at 
the "rats nest" stage of layout...just place a polygon (simply a 
rectangle really) on the same layer as your traces.  Make it the 
size of your entire board.  When you auto route...the autorouter 
will automatically isolate all your traces from this "ground plane". 
So, it is not really a "ground plane" as it is isolated from 
everything else. But, with one little "blue wire" you can make it a 
ground plane, if you want.  I just do it because it will save on 
etch time. 

Jim

P.S.  BTW, I don't use the default Eagle design rules.  I modified 
them to make traces twice as wide...and also to leave twice 
the "isolation" between traces. With the fatter traces...it is 
easier to get a perfect Toner Transfer.   I Googled "Eagle Design 
Rules" and somebody had posted a writeup on how to change them to 
new, consistent values. Very nice of him.