The process is pretty easy. I buy regular-sized Hershey bars in bulk. These don't have the foil wrapping and the extra paper around it. Instead, they just have a plastic wrapper around them.
I leave them wrapped in their original wrapper, but cover the outside in white wrapping paper. This hides the brown plastic and gives my bar a nice, clean packaging. Wrap it just like a present, and I highly recommend using white wrapping paper from the $1 store. Then I cover the candy bar with the wrapper that I designed, fitting the theme of the party. Because I've done this so many times, I've got the template saved to my computer, and I just customize it according to the theme of the party, printing it out on cardstock paper from my printer. You can use scotch tape over the edges but I prefer double-sides tape beneath the edge to have a cleaner look.
For Josiah's party, I couldn't resist creating these adorable candy bar favors. I made Mickey Mouse for the boys and Minnie Mouse for the girls.
You can't see the buttons or polka dots when the wrapper is folded, but they're an extra cute element when the bar is unwrapped.
These were a big hit with the party guests and turned out great.
*Template is available for sale at my Etsy shop.