The piece I'm calling the mini-fender has four unnecessary holes. One big one was used for routing wiring and the other three small ones were for rivets to attach the plastic rear fender extension on stock fenders. This was to be my first real test with my cheap-ass Harbor Freight flux core welder.
I have no real welding experience or training. I watched the MIG Welding Fundamentals DVD from Lowbrow Customs and played with a few piece of scrap metal. I also watch a lot of car and motorcycle TV shows where guys are welding if that counts.
First I made a plug for the large hole out of 16 gauge steel.
Then I decided to start small with the three rivet holes. I used my hand drill with a Scotch-Brite disc to remove the paint around the welding areas. Then I clamped it to a thicker piece of steel to act as a backing plate but hopefully be thick enough not to weld to the fender..
It took a few tries to build up material and not burn through the fender.
Here's the center rivet hole filled.
I used a magnet to hold the plug in place.
Then I tacked it in place.
Here is is sealed. I checked it against a bright light and kept welding until I filled in all the pinholes.
Here it is after a little grinding and sanding. A little body filler and paint and you should never know the holes were there.