An Advanced Paint Tool?

Would it be possible for someone to extend the paint tool’s capabilities? At the moment (since 2008, its 2015 now) the only function for the paint tool was to select a certain texture, like glass shatter or bullet impacts, then spray (slap) it on whatever the player desires. Their is a limit on how many textures can go on a certain object, textures would disappear if this limit was exceeded. The issue I have with this tool is that there is no way to use it to paint details onto the ragdoll’s face. For instance, if I wanted a ragdoll to have a black eye, there would be no way of doing so, the texture would cover the whole face. The same goes with blood/bulletholes. I thought they would eventually add the option to change the size of the texture so the player could make a ragdoll look like its bleeding from their nose, instead of only having a blood texture dumped on their head.

How difficult would it be to make a setting for the paint tool where the player could change the size of their desired texture?

It is possible to do this with util.DecalEx, however you need to take in mind that GMod is on an engine from 2004, its not exactly unreal engine.