One plain short-sleeve t-shirt from a craft store
2-5 fat quarters or any large scraps you have laying around (the scraps should be about 2 inches wider than the width of your shirt and 4 inches tall or taller)
How to make:
1.) Lay your shirt flat on a table
2.) Cut the side seams between the front and the back (if there is no side seam, cut where they would be) up to the bottom of sleeve arm hole.
3.) Along only the front, cut from the bottom of one sleeve hole to about two or three inches below the second sleeve hole.
4.) Cut a rectangle that is 1/2 inch wider than the width of the shirt by about 6 or eight inches (You can use a bigger piece if you only want only one stripe)
5.) After you cut the rectangles, you can layout two rectangles right sides together and cut at an angle along the long side. Make sure that the shorter height is at least 3 inches high
6.) Pin rectangle to the bottom of the front of the shirt. Pin right sides together along the long edge only.
7.) Sew along pinned edge.
8.) Repeat steps 4-6 until the front of the shirt is as long as the back, making sure to match short height to long height.
9.) Turn shirt inside out and pin right sides together and along the side seam and sew.
10.) Turn shirt right side out
11.) Cut the hem off the bottom of each sleeve.
12.) Measure a rectangle that is 1 inch wider than the two times width of the sleeve by 1 inch longer than you want the sleeve
14.) Fold each rectangle in half right sides together so that short sides meet and the top and bottom are the width of the sleeve
15.) Pin along the short side (the side that isn’t the width of the sleeve) and sew.
16.) Repeat on other sleeve
17.) Put each sleeve addition around the outside of each sleeve matching sleeve seams
18.) Pin along the bottom edge and sew.
19.) Pin up 1/4 inch and then another quarter inch on each sleeve.
20) Iron each sleeve hem down, and then sew.
21.) Cut off the very bottom of the t-shirt hem.
22.) Pin 1/2 inch from the bottom and then 1/2 inch again and press into place and sew along the bottom.
23.) Wear and enjoy.