If you can't reinvent the wheel on company time, I would urge you to try and do it on your own time. You don't necessarily have to use the solution you come up with, but it helps to get a deeper understanding of the code beneath the libraries you use. Using this technique definitely made me a better developer when I was younger. I still like to take small portions of libraries I use and try to code them myself, just to get a better feeling for how things work (even if the code is vastly different from the library I use).