I bought my Lacquer sticks from 'micro-tools.com'. They cost a couple of bucks each, the shipping was fast, and over-all service was good.
The part #'s for the sticks I bought are:
White L51120 $1.95ea
Red L51122 $2.95ea
Blue L51125 $1.95ea
When I repainted the faces on my GPT-750, I didn't know how far one stick would go, so I ordered 4 white ones, one red, and one blue. It wound up that they go a LOT farther than I figured, as I only used 3/4 of one white stick to do the entire transmitter, and a 390a faceplate that I painted at the same time to match the TMC, (which is installed in the empty center drawer, hence the need to match the paint on the receiver)
Lacquer sticks form a thin hard shell when they sit around for a while, so before use, take a razor blade and trim 1/8th inch from the tip at a slight angle to expose the fresh paint, (which will stay fresh for a few days, so if you do a few letters, then come back the next day, no trimming needed, just get right back to it.
Make sure the faceplate is clean and dry, (Now's a good time to scrub your hands), and, as Don said, it's VERY important to use a soft tool like a toothpick to get any loose paint out of the letters. I used a cloth dampened with acetone and wiped over the letters to remove any remaining grease. Lacquer sticks take a couple of weeks to fully harden so you have a buttload of time to take it slow and pay attention to the details. After everything was clean, (including my greasy hands), I rubbed the paint stick into all the letters, with enough pressure to get the paint stick to smoosh into the lettering, and while moving in all directions (little circles, etc.), to make sure the engraved wording gets filled evenly. When done right, you'll barely be able to see the lettering under the paint blotch. The amount of pressure is important because the stick has the consistency of "Chapstick", and you want the paint pushed right down to the bottom of the engraving, and filled to the point where it's level with the panel surface. After you get your lettering all filled, STOP, put down the stick, and step away from the vehicle sir.
By trial and error, I found it's best to wait a day or so, before wiping away the excess. Lacquer sticks don't have the typical solvents in them that normal paint has, so they dry very VERY slowly. They will be ready to wipe when the blotch becomes dry in appearance, and has a "not so juicy" feel to it, as compared to when you applied the paint in the first place. Temperature and humidity will dictate this, but usually, the next day will be perfect. If your room is colder, wait two days.
My finishing method: I tried plastic squeeges, rubber and wood blocks, numerous types of cloth rags, etc., and any of those are fine if you don't plan on showing off your work to anyone. The best way I found was to take about 20 sheets of decent quality printer paper, a stool, and a garbage can, and setup in front of your panel. I would rip a small strip out of the paper about an inch and a half wide by 4 or 5 inches long. Hold the piece of paper so it is positioned under your thumb, and wipe slowly across the blotch using a rolling motion under your thumb while moving that lifts the paper away as the paint starts to stick to it. Don't try to do too much, only move an inch to two, then drop the paper in the garbage and rip a new piece. Moderate pressure is key to packing paint down into the letters, and the smooth texture of the paper leaves a perfectly smooth surface to the filled letters, unlike using a rag, which leaves behind a kind of grainy finish. Don't use any solvents just yet, or you'll soften partially hardened paint thatís in the letters, and you'll get a very light kind of streaking as the softened paint is pulled from the engraving. Another reason for not using a cloth at this stage is, the cloth, moistened with solvent or not, will puff up as it passes over the lettering, and remove a slight amount of paint below the surface level. Because engraved letters have a "V" shape, they end result will be thinner looking lettering.
If you have any accidents, and dig the paint out of any letters, just take the paint stick and rub it right back in again, then come back to that one later. I think this is the over all beauty of paint sticks as they allow you to mess up numerous times during the learning curve, as I did, and fix accident real easy.
After you have the bulk of the excess paint wiped away, the lettering should look sharp, but with a light haze around it. Not to mention, at this point you have quite some time into this job, so the self-appreciation is kicking in while you admire your work.
Let the letters dry for a few more days, then come back with the paper again, wet it with acetone, or lacquer thinner, and lightly rub over the lettering to remove the haze. Don't push too hard, and don't try to get it perfect, just take off as much of the haze as possible. I left the equipment alone in that condition for a week or so while I jumped to another project, and when I got back to it, it was time to finish the damn thing off.
The Money Shot. (We'll see how many internet search 'hits' that phrase gets.
Pick up a bottle of quality "Cleaner Wax" Don't grab some junk out of the 99.5% off bin, and don't use regular car wax, it has to be "Cleaner Wax". I used this Meguiar's Cleaner Wax, and it works great. (I use it on my cars and trucks also, good stuff) Also get some nice soft terry towels, and a wax applicator sponge. (Not a dish sponge, these are fine sponges just for waxing.) Wax the whole face of the radio; go lightly over the letters to remove the haze, but take it easy. If the paint fill looks like it's getting pulled out, hold off another day or two, and try it again. (That's the downside to these damn sticks is that they take forever to finally 'set up'.) The right amount of pressure and you'll see a little coloring from the panel start to show up on the sponge, this is good. Let the wax sit for 20 minutes or so, and take it off with the terry towels. Don't let the towels load up with wax, and take it easy around the letters, but get all that wax off of there.
This is the best I can say as far as doing a top notch grade 10 paint fill. If you took your time, the lettering will look sharp, and bright, and fat, and it'll look like it was put on there with magic. Much MUCH better than the OEM did it.
Keep your fingers off the lettering for about 3 months until it sets hard, and it'll last another 50 years.
Here's the link to the micro tools page where I ordered the Lacquer sticks.http://www.micro-tools.com/store/SearchByCategory.aspx?CategoryCode=PAI