Completely Accurate Element RNG is completely accurate. It uses data sampled from Wikipedia page on abundance of elements in Earth's crust to determine weights of elements. That means the most common things you can roll are oxygen and silicon, and the rarest things you can roll are protactinium and radium. This is based on a factor of ppm*10,000,000 to determine weights, so actinium, polonium, and radon, which have defined abundance values, are missing due to being too small to have an integer abundance value. Instructions are in the project.
Credit to @-Rex- for Stamp Font Engine++. Font used is Bahnschrift, made by Microsoft. Code for calculating weight and rolling an specific element are borrowed from mine. INSANIFIED, albeit simplified.