If you want to do this in Illustrator, you can make a "Scatter Brush" in the "Brushes" pallet. You can make a small polygon or shape and create the brush from that, you can set the scaling, the rotation, the spacing and spread, and set the color choices to "Tint". That color choice lets the brushed color be whatever your stroke color is. You can change the weight on your stroke (after you have drawn it) to change the size of the whole effect on just that stroke, and you can apply many "brushed" lines to achieve the desired look and color(s) 'till the customer is happy. You can save off pallets of brushes for later use. You can change the settings on a brush and have Illustrator apply the changes to the lines you already have it applied to, or let it leave those alone and only apply it to brushed lines created afterwords.
You can expand those brushed lines for cutting and or editing/fine tuning.