Do you have PhotoShop? I'm not sure if Photoshop has something similar, but "PaintPro" creates something called "picture tubes" which are 'scalable canned images'. Checking Google for "picture tubes" I found many FREE examples for use:
This might not be of any help, -but I know that PaintPro can open/edit anything that PhotoShop can create and, if the opposite is true, then places like the URL above could be a resource. You just merely fill-in a gradient color or whatever else you need.