hi Eddi, you are in a forum, not a discussion group or room
yes you can make your own icons... i use Photoshop but there are some other options
no you don't have to make different sizes but you can if your design gets buggered up by resizing it
answers to clear questions are fast but vague questions take longer because people are not sure what you want to use the icon for so they have to take time to think about it or lurk until extra details come in
What Adobe program do you have?
I've used this plugin with Photoshop. Note that I don't have it installed at the moment, and I might not have used it since Photoshop moved to HTML5 with CC2014.2 so it might not still be compatible.
Your icons need to be of any or all of valid sizes
16 X 16 pixels
32 X 32
48 X 48
256 x 256
There are other requirements that yo'll find on the favicon site (link above)
To use your new icons as drive icons, the following text file needs to be in the root of that drive
Along with the .ico file
Good luck and enjoy. I must have wasted a good few hours setting up my drives with pretty pictures.