With saltwater etching we can simply etch out the material in the center and then shape the rest with conventional tools. I put together a photo tutorial of how I did it. Keep in mind that this is only the second attempt I've made at making these so I haven't perfected the details yet but the meat and potatoes of it are solid.
So here we go....
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What you will need:
+I use hacksaw blades for my material because they are easy to acquire and inexpensive but if you are using another material I don't see any reason why the process would be any different.
+Salt
+Glass jar taller than your blades are long (plastic will work if you are not using a candle warmer to keep the solution hot)
+DC power supply (I used a 9v 2100ma or 2.1a but any small supply will work. I did find that the higher the current, amps, the faster the etch.)
+solid metal wire (copper works best)
+extra bare hacksaw blade (all paint removed)
+candle warmer (optional)
+alligator clips (optional)
+needle files
+vise
+dremel with cutoff wheel
+2 pairs of pliers (preferably both needle nose, at least one should be needle nose)
+stove or torch for heat bending
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First, cut or break the blades in half and grind/dremel/file off the teeth. Then remove the paint from the area to be etched and around the hole in the end (read on for explanation).

Next we need to cover the blade in electrical tape leaving the end with the hole exposed. Before covering both sides, use a marker to mark the side with the paint removed. Be sure that the edges are completely sealed and that there are no bubbles in the area to be etched. We want this to be completely water proof.



Next we need to cut out an area of the tape to be etched. I had a wrench I made a while back that I used as a template but the measurements of the cutout are 3/16" x 9/16" in an oval shape (just round the corners, square corners will be more prone to breaking). The cutout should be about 3/32" from the edge of the blade. Err on the side of too far in rather than too close, some filing will be needed anyway so don't be afraid to put it a little further in as such a small measurement is hard to be accurate with considering the blade is under a thick tape.


Now we prep them for the etch. Take your bare wire (I used a solid 20ga copper wire I had laying around and stripped the insulation off) and tie it through the holes in the blades. This will give plenty of electrical continuity if you removed all the paint around the tops of the holes. Leave about an inch or so of wire on each end as this will also be what suspends the blades in the etch solution.

Now lets prepare the etch solution and setup.
gather the etching supplies on a counter top or other area with an electrical outlet that is very stable (once the etch is underway the solution will turn to a liquid rust solution and if you spill it you wont likely ever get the stains out).

Fill the jar with enough hot water to cover the area of the blades to be etched plus another inch. Pour in some salt and stir until it dissolves. Pour more in and stir until it dissolves. When it will not dissolve any more you have reached the saturation point which is what we want. The more salt dissolved in the water, the faster the etch will complete. I used a candle warmer to keep the water hot throughout the process. It keeps the water at a steady 135 F. I have found that this greatly reduces the etch time.
Now hang the blades on the lip of the jar and using an alligator clip, clip the bare blade to the side of the jar.

The bare blade needs to be connected to the negative side of the power supply and the positive side to the wire hanging the blades to be etched.
If you aren't sure which is which go ahead and hook it up either way and plug it in. Whichever side is connected to the negative will bubble. You want the bare blade to bubble, not the blades to be etched. If you got it wrong, simply swap them out.
I used some alligator clips for this as it is much easier but if you don't have any and don't want to buy any, you could simply twist the wire hanging the blades to the positive wire of the supply and tie the negative wire of the supply to the hole in the bare blade. If you do this, use something to hold the bare blade in place so it cannot come in contact with the blades to be etched causing a direct short.
Plug it in and you should immediately see the bare blade bubbling away.

With my setup it took exactly 20 minutes to etch all the way through. Lower current (lower amps) power supplies will take longer and cooler solution temperatures will take longer. You can check them as often as you like. Just unplug the supply first then pull them out and rinse the muck off and see how far you have to go. You are better off taking them out a little early and having more filing to do than leaving them too long and etching too much material. After the solution etches through the exposed area it will begin to etch under the tape so keep an eye on it.
Here they are fresh out of the etch and nothing but a quick rinse in the sink. You can see the blue paint in the hole, that's the paint from the other side of the blade and is all that's left of that area of the blade.

Remove the tape and see what you have.


Now we need to use the needle files to clean up the rough edges. The little bit of metal left around the edges is very thin and files away with just a few strokes.

Remove the rest of the paint and give the wrench as shinny a finish as you want now. After this step, sanding and polishing will be much more difficult. I just used some 320 grit sandpaper to get it even. Wrenches don't need to be smooth like a pick unless you just like them that way.

Using a cutoff wheel, cut a slot in the outer edge of the cutout area. Make the cut slightly closer to the top of the cutout than the bottom. The prong that goes into the top of the keyway doesn't need to be as long as the one that goes into the bottom.


Now we need to bend the prongs. This part really takes a bit of practice so be prepared to break one or bend them too far apart/close together (that's why I made 4 in a batch instead of one at a time). The best way to determine where to bend them is to use a caliper to measure the height of the keyway of the lock you intend to use the wrench on. If you don' t have a caliper, you can take a key and lay it across the unbent prongs just before the shoulder so you have the full width of the key blade and use a sharp knife to make marks on the prongs. No need to cut deep, just a light scratch that you can see will do. Markers make too thick of a line to be helpful and will likely burn off when heating it to bend it.
I used an electric stove top to do my heating because I am out of oxygen for my torch. Turn the burner on high and let it heat up. Gather your pliers and put on some leather gloves.
Lay the wrench on the burner making sure the prongs are in contact with the burner.


When the prongs turn blue, remove it from the heat and hold it with one pair of pliers right at the bend mark and bend just slightly with the other pair of pliers. The pliers will act as a heatsink and cool the tiny prongs quickly so only a slight bend can be done at a time. Put it back on the burner for about 10 seconds and bend again. Repeat until you have a 90 degree bend then repeat on the other prong. I can't stress enough that you need to go slow when bending.
Once bent, you will need to heat it one more time and quench it quickly in cold water. This wont give you a perfect temper but it will be plenty strong enough for the purpose. If you really want to temper it back to rock hard you'll need to use a torch to heat it to a cherry red (you can test it with a magnet, when hot enough a magnet will have no effect on the metal) then quench it in hot water. Last, put it in a 400 F oven for about 30 minutes and quench in cold water. This is what I do with my picks when I have overheated them or otherwise heated them and I haven't broken one yet nor do they bend easily.
Now you will need to grind or file the top prong a little thinner than the bottom one as the top of the keyway is about half the width of the bottom. I used a grinding wheel on a dremel to thin it out and taper it slightly.
Last, give it a quick once over with whatever your finish sanding was to remove the oxidation from the heating process.
And the finished product:


That's it. I hope some of you give it a shot. Have fun.