What you need is a dull #11 blade, Tamiya "Super Thin" cement with the fine brush, and some plastruct .010" and .015" rod (depends what size weld you want, to me .020" from evergreen is always too big, and stretched sprue is just not consistant enough)
For this weld I am using the .010" as it is not too prominent. First cut the rod to length and use just a touch of glue to tack it in place:
Next is time to melt the rod, carefully brush on the cement, let sit for a few seconds, and use your dull #11 to add start adding texture, aim for a semi-circle type pattern, if the #11 tip is dull, it should be easy:
And now do it again, add some more glue, wait a few seconds, and further define the texture:
When you are happy with texture, seal it with another thin layer of thin cement, and you are done:
These tiny welds can add alot of character, and it seems most people don't even bother with them, but I think the result is worthwhile!
The process is actually very quick and fun!