In my school, our metal shop has made a lot of ornamental shiny decorations. I've been the main person making them, and people really like them, and so I figured I'd share my process.
For this, you'll need a piece of mild steel that is already cut out how you want, a vice grip and some bracing, an angle grinder with grinding and sanding disks, paint/lacquer thinner, and some clear coat spray finish. A sandblaster also helps, but can be worked around.
Step 1: Your Piece
My Metal Shop uses mild steel, and we cut out this piece from our CNC Plasma cutter. Made out of 1/8" thick Material, this is my school mascot.
Make sure to clean any slag or other junk off of your piece before we start!
Step 2: Prepping Your Surface
Your piece can either be sandblasted, or ground down with an angle grinder. Either way, you need to get that grey off of your steel.
For grinding, make sure you're grinding marks are perpendicular to how you want your final marks to look. In this case, I'm going vertical, because my final marks will be horizontal. DON"T DIG IN TO YOUR STEEL!!! It will effect your final product!
Step 3: Holding Your Piece
Honestly, just figure out some way to hold your piece steady. I like bracing my piece, but it depends on what shape you're shining.
Step 4: First Pass
Switching out to your sanding disk, it's time to make your first pass! This is the most important pass, because it gets rid of markings and imperfections in the surface. Also make sure to sand your piece in the direction you want it to turn out! If you used a hard grinder to knock that grey off, make sure to sand perpendicular to your previous markings.
Sand only while dragging your sander towards you. Using the very end of your disk, make sure to keep a uniform movement, and uniform speed.
It should look something like the one on the left.
Step 5: Second Pass
This one's shorter than the previous pass. This time, go over your entire piece, but space out your strokes to get some sort of contrast going. you want it to look similar to the picture above.
It should look something like the one on the right.
Step 6: Final Pass
This is the kicker! while the other passes were done with the end of my disk, this one is done with the side. It makes it very shiny, with some good contrast! I only do 2-4 strokes per piece with this pass. Just enough to be eye catching.
Step 7: Bending / Final Touches
All this sanding has created burs on the edge of your piece. I just take a bit of coarse sandpaper and knock those down. Then I bend the base piece of my ornament. This design is to sit on a desk. I like to bend my piece to where it's leaning back a bit. That way, the light catches on my strokes and makes it shiny!
Step 8: Finishing
Last but not least: Sealing your metal. You've exposed a lot of steel by shining it like this! In order to keep it from rusting, I first wipe it down with paint/lacquer thinner to get rid of any moisture or oils that may be there. Then I use some Crystal Clear Enamel from Rustoleum to seal it off. Shoot the back and front, and you're good!
Step 9: Enjoy!
Now you have a nice and shiny piece to enjoy wherever you decide to put it! Selling these is actually how my school's Metal Shop got some of it's money for supplies.
Just remember: People like the Shiny!