I understand this desire, but in the case of the component you are trying to create the code you’d be copying from SvgSlider is quite trivial. Your custom draw code would be more lines than what you’d have to copy.
Another option: according to @synthi in this thread: Buttons, SVG and layers - #4 by synthi it is possible to interact with individual elements of an SVG. I’ve never tried this so I can’t be of any help, but perhaps you could create some “template” SVGs, and then change their color in your component’s step() method as Antonio suggests. This way your component could inherit from SvgSlider.