I have never welded flares before but I jumped on the group buy for these. Today I started with the 1st one and I did the drivers side rear. I ended up drilling 5 holes and useing self tapping screws to hold the flare in place before cutting. I opted for my cut off saw which was the wrong choice for precision cuts. It's not too bad but I have some gaps of 1/16 to 1/8 that I have to bridge with my mig welder. I have the flare tacked in place and it lines up quite well. But what do I use to "back up" the gaps when I weld them? Previous posts suggested a copper spoon but I don't know what that is or where to purchase? Any DIY suggestions on what to use? I will use a jig saw for the remaining 3 flare cuts for more precision. Any suggestions are welcome.

I have heard of adding metal via coathanger made into a rod , then add it while

you have a pool. if your biggest gap is an 1/8" it should work. I have done this

with oxy / ac (gas) to fill small rust holes. My .02

Tack welds. Do them at 1 foot intervals. Get a piece of copper or brass or even aluminum. and put that behind your tack weld, That will help you tack between the gaps. Tack welds should be about 1/8 to 1/4in.

A spoon is nice because it has a long handle so you wont burn yourself when you weld. But just about anything works...

Coat hanger works as well for the nasty big holes, Its basically a filler rod (tig welding)

Here's how I put mine on. Center the fender on the car, hold in place with cleco fastners, draw the outline of the fender on the car. Take the fender down and draw another line to match the previous line just about one inch to the inside. Now take you cut off wheel and cut the inside mark. Put your fender back on with the cleco's and skip weld. This gives you a lap joint, not a butt weld.
Good Luck!

Take a piece of copper pipe, say 1" dia. Flatten half of it and bend the flattened portion to a comfortable angle. There's your copper backing.