I have been taking dents out of stainless molding for years, helping out my friends with their troubled pieces, and showing them how its done....passing on the info. Yes, some people cannot do this right, just like I'll never be able to play a musical instrument.....but most can and it just requires the right steps and patience. The tricky part is to remove the dent from the backside...I have made up many 'punching' tools to do this operation...from grinding round old punches to plain bolts making a modified head to suit. There is one big trick...to which most people are afraid of...but mentioned above by those who know....the using of a file....a good, new, fine file that will be the main tool to remove waves and making sure that the surface is not distorted. You will have to go back & forth with the hammer / punch to bring the surface at the proper height....using the file very lightly to identify high & low spots. This is where the patience comes in. Work slowly, tediously....and once these highs & lows are addressed...do use the file to obtain a perfectly staight surface, mush like doing the bondo on bodywork. It is surprising how material can be removed without affecting the thickness & strength....SS is tough stuff. Once this is done, use 180 sandpaper on a rubber sanding block to remove the deeper scratches left by the filing operation. 180 is rough, but not nearly as tough as SS.
Don't be shy here, work with the sanding block to obtain a perfectly straight surface. Buffing...whoh...not yet.....change to a finer grade...320 or 400....sand till the surface is almost polished. Buffing and the 'green' compound is for the final, final step....excessive buffing and heating does nothing to save your molding....and once the block sanding is complete, with the surface mirror finished, buff, clean and enjoy. No experience doing this...try it out on a scrap piece. Repro '36 headlight rings have just come out on the market, but a couple of year ago, a buddy needed his fixed....I worked with him & he was amazed on the perfect result....reviving back old parts is rewarding, and make these efforts more than worthwhile. Hope this helps. Robert