I searched at a couple different craft stores for hats, but I was only able to find a red one. I had to make it work so I grabbed a white one too, searched for some green fabric spray paint, and crossed my fingers that it would work. It did!
To make your Mario and Luigi hats you’ll need
White and red hats
Green fabric spray paint
White fabric paint (not spray paint)
Freezer stencils with “M” and “L” pattern (I found mine from Mum of All Trades)
Temporary fabric spray glue (to adhere the stencil–you’ll never get it ironed on there)
A large and small paintbrush
Spray the back of your “L” stencil onto the front center of the white hat, and spray away! I found it best to spray a bit and then use my brush to paint it across the hat.