Hi Jeff,
This is a link to a build I finished a couple of months ago:
https://armorama.kitmaker.net/forums/158659&page=1 All of the cast texture on the turret, final drive, and driver / co-driver's hoods is done with thinned Testor's Green Stuff putty. Also, all of the green colored weld beads are also done with thinned putty. (The "whitish" weld beads are Milliput 2-part epoxy which is easier to form around tight radious and for very small welds.)
I use Testor's Green Stuff thinned with laquer thinner and Testor's liquid cement (about 3:1 laquer thinner to cement). I mix the putty with the thinner to a consistancy of warm honey for weld beads and about twice that thin for cast textures. I use a tooth pick (cocktail stick) carved to a chisle end and wetted with laquer thinner to texture the welds followed with liquid cement.
I apply the thinned putty using an old nylon brush trimmed to a rough point and clean it in a separate jar with laquer thinner. I use old Teator's liquid cement glass bottles to mix the thinned putty in.
Common blue painter's tape works well as a mask to keep the thinned putty off of areas where you don't want it. I also use two parallel pieces of the same tape to mask the sides of the weld beads made with the thinned putty. Pull any masks up before the putty dries so that it doesn't cause chipping along the edges.
I like the versatiliy of thinning the putty myself since various viscosities are useful for different applications. I've been using this method for a long time (since before Mr. Surfacer wasn't even a gleam in the eye of the Mr. Color company - in fact probably for about 20 years before Mr. Color company was even thought of). Besides which, none of my local hobby shops carry the Mr. Color line of products.
It's a tried and true "old school" technique, but as always, your "mileage may vary." I'd suggest whatever technique you try to experiment with it a bit before you try it on your actual project.
HTH and good luck,
Mike