Basic wardrobe options like T-shirts can sometimes be difficult to find in exactly the styles, patterns and colors you want. Rather than spending a lot of time searching out the perfect shirt in stores or settling for styles that aren't quite right, you can have exactly the clothes you want by making them yourself. Making a T-shirt does not necessarily involve a lot of commercial patterns, sewing skill and fitting. You can make your own V-neck T-shirt by altering an existing plain T-shirt to use as a simple impromptu pattern.
Find an old, plain T-shirt in your size. If you are going to be making your new V-neck shirt in plain cotton, do not choose a T-shirt that has any sort of stretch to it. If you do choose to make a stretchy shirt, make sure that the stretch in your T-shirt and your fabric is similar.
Fold back the sleeves on the T-shirt, and fold the T-shirt in half along the width so that you have two equal sides. Lay the T-shirt on a double layer of your fabric, with the folded side of the shirt against the folded side of the fabric. Trace around the outside of the other sides of the shirt with your fabric pencil, then draw around that outline 1/2 inch away. Cut along the outermost line, leaving the folded side intact. This will be the back piece of your shirt.
Lay the back piece on another part of the folded fabric, like you did to make that piece. Cut around the outsides to create the front piece of the shirt. On your body, measure from the base of your neck down to where you would like the V-neck to end. On the wrong side of the front piece of the shirt, find the center front and mark this measurement. Also mark points 1 inch away from the outside edge of the shoulder at the top. Connect these points to the bottom of your center front marking, creating a "V" shape. On the inside of the V, draw it again 5/8 inch away. Cut along this inside line.
Lay one of the sleeves on your fabric, with the folded edge of the sleeve against a fold line. Trace around the sleeve, and draw the armhole edge, then remove the sleeve from the fabric. Draw around the outline, 1/2 inch away from it. Cut along this line, leaving the folded edge intact. This will be one of your sleeves. Lay the sleeve on another section of fabric and cut around it to create a second sleeve.
Stitch the front and back pieces together at the shoulder seams, right sides together and 1/2 inch away from the edges. Press the seam allowance open and trim to 1/4 inch, then zigzag stitch or serge the raw edges. Fold the neckline edge under 1/4 inch and press, then fold it under another 1/2 inch and press. Stitch neatly along the folded edge.
Open up the shirt body and lay the armholes of the sleeve pieces against the armhole edges of the body, right sides together. Stitch, press and finish the armhole seams. Fold the shirt back down, right sides together, and stitch the side seams from sleeve end to body hem. Press and finish the seam allowances.
Fold under the sleeve ends and body hem 1/4 inch and press, then fold them under another 1/2 inch and press. Stitch them down along the fold line.