Make sure you heat the metal and not the solder directly. When the metal is hot enough, the solder will melt when touched to it then flow all around your joint. Have a damp rag handy and wipe the joint as soon as you pull the solder away. It will clean up any clumps or drips and make it look...
Used this jig to do two kegs yesterday! Worked fantastic. I had to wrap a little tape around the PVC to thicken it so it would sit tight inside the hole. Cleaned it up with a dremel and am now ready to drill some holes for hardware!