RGB Block Help

I made an RGB Table that will allow people to enter the exact red, green, and blue code that they want and will create a block of that color. Is there a way for me to do this? I have a "base block" that will be used as the input, then the numbers will be used to turn that base block into the block of the color they chose. The table GUI is done as well. I am just not that great at coding. Can anyone help me by any chance or is what I am asking impossible? I don't want to make a seperate model for all 16 million colors either.