Harbor freight sells a cheap aluminum one, but I think they only go up to 1/4"x20 max size.
http://www.harborfreight.com/45-piece-threaded-insert-riveter-kit-1210.htmlIf you need something bigger or stronger, I have some 3/8"x16 steel nutserts in the garage, but I don't have the tool to install them. I used them for my radiator skid plate - installed 4 on the bumper and 2 on the lower frame cross member. I had ordered a 10 pack so there's still 4 left over. It was pretty difficult to install them without the tool. I watched about 10 youtube videos and finally had success with the bolt/oversized nut/washer method. Basically, you slip the washer and nut over the bolt, then thread the bolt into the nutsert and hold the nut with a wrench while you crank on the bolt with tons of leverage. With a 3/8x16 bolt, I found a 14mm nut that worked pervectly to slip over the bolt shaft (I think it was an m10). I ended up needing to use an impact wrench to set them pretty good at first, then finished them off with a long handled ratchet to be sure I didn't over tighten them. If I had an extra set of hands when I did it, I probably could have just used the ratchet because one person could have held the wrench while I used one hand to hold the ratched in place (and therefore hold the nutsert in the hole) while using the other hand to crank on the ratchet. I needed the impact because it was the only way I could hold the nutsert down in the hole while also holding the wrench and turning the bolt.
I can bring the nutserts I have to the mod day if you want. They're the deeper grip range - 0.150" - 0.311", so they're only good for thick metal. Here's the exact ones I have:
http://www.ebay.com/itm/371404271821?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
