Select a cotton t-shirt to fit your pooch. You can use one with a graphic as long as it can be covered up. Lay the t-shirt on your work surface.
Lay out the felt in rows to cover the shirt. I ended up using eight pieces; you may need more depending on the size of the shirt.
Start with your bottom piece(s). Cut it to fit the width of the shirt.
Decide how long you want the strips vertically - I chose about 2 1/2" long. Trim the felt down to size with scissors or a craft knife.
Once the bottom piece is cut to your specifications, use it as a template to cut the same sized pieces from the other colors.
Cut fringe in all of your felt pieces. Cut slightly more than halfway up the felt, and try to eyeball equal sections of fringe. They don't have to be exact, but as close as possible.
Add sparkle to the edges of the fringe. Either paint or dip the edges of the fringe in Mod Podge, then dip in glitter. Place on a piece of wax paper to dry.
Once the fringe is dry, take it outside and shake the excess off of every piece.
You're ready to hot glue! Start at the bottom of your shirt. Run a line of hot glue across the top of the strip, turn over quickly and press down on the shirt. Repeat until the shirt is covered.
Trim the felt to fit around the armhole with scissors.
Use hot glue to apply glue in the areas to secure the felt that has just been cut. Do this on both sides and let your shirt cool.
Glue a ribbon to the mini sombrero so you can tie it around your dog's head.