Thanks for the compliment! It took much longer than I thought, and despite the shitty paint i chose, it ended up looking pretty decent.
The technique is called a "reverse wash". what you do is you prime and spray down your "detail" color (I used lacquer just to be safe since we will be putting a solvent on top of that).
Once that has dried, you spray down a gloss clear-coat. This will make the top layer of paint MUCH MUCH easier to remove.
After that has dried, you spray your primary color (for sinanju chest/arm/knees that would be black, in this case gloss black to match the shiny finish of the titanium kit) as an enamel (needs to be a weaker paint than the top coat you just sprayed since nearly all top coat is lacquer-based).
I let that dry for about 5 or 6 hours - enough for the black enamel to dry a bit but not cure fully as this makes it easier to remove.
Then, i took some hobby swabs (you have to use hobby swabs - they are really fine and are wound REALLY tight so you dont get cotton fibers stuck in the somewhat-still-tacky paint surface), soaked them in some enamel thinner, and then started rubbing that VERY CAREFULLY on the raised detal of the Sleeve pieces. The black paint will come off, revealing the gold underneath.
Here's a good
how-to.