I can tell you how I do 3 but I can't tell you how I do the skinny veins.
Wutz-it mold w/lami plate, twin shoot the lami plate then remove and shoot your belly color. That's for three color pictured above, you can't use your normal back color or it will come out too light so you have to darken it a bit with it being so small.
As for the skinny vein you have to start the same way then as you place..... yup can't give it away

Drew