To my surprise, it wasn't as hard as I thought it would be. Now, while I am very crafty, I am not terribly handy with a sewing machine. I can sew a basic straight line, and subtle curves, which is all I needed to do with this. In hindsight, I realized the whole costume could be done with a glue gun.
Here's what you need and how I did it:
3/4 to 1 yard of felt, depending on size of child (for a child 1 yard, for an adult probably 2 yards)
1 small piece of white felt (8x10 sheet from craft store)
access to a printer or copy machine
sewing machine, glue gun, or iron-on adhesive tape
Step 1: Fold the yard of felt in half. Have your child lay down on it with their shoulders at the fold. Draw a circle around them from their shoulders down and around their waist. (Adam is 5 years old and is a boys size 6, I actually only used between 1/2 and 3/4 of a yard.)
Step 2: Cut the circle out with sharp scissors, cutting the fold so you have two pieces of fabric. Then pin the costume on the shoulders, leaving an opening for the neck. Continue to pin down the sides of the costume, leaving arm openings, and leave the bottom completely open.
Step 3: Once the costume is pinned, CAREFULLY try it on your child to make sure the head and arm openings are big enough. Then simply stitch, glue gun, or using adhesive tape, secure the seams.
Step 4: Turn the costume right side out, so the seams are on the inside. Now on your computer, scroll through the fonts of lower case M's to find one that looks like the logo. Print out the letter to fill the entire 8 1/2" x 11" paper. If your printer can't print that large, then take it to the copy store and have them enlarge it. (I went to our copy store and the very nice clerk, kept enlarging for me until it fit.)
Step 5: Cut out the "m", now you have a pattern. Lay it on the white felt, trace around it with pen or marker. Cut out the "m" and glue it to the front of the costume. That's it your done!!!