
Since the whole idea of the sweaters was to use up leftover yarn, I created a template instead of writing out a pattern. This way, I could use different weights of yarn and the sweaters would more or less come out the same size. When yarn ran out, I changed colors creating interesting designs. See more example here. For this example, I used an E hook and Sugar 'n Cream cotton.
Template

This template is at actual size. To make your own, fold a piece of paper. The fold being the top of the sweater, cut a sweater shape at the desired size. At the middle of the fold, cut a slit to show the placement of the neck hole. When cutting your template, please make sure your arms are the same length. Unfold the template and lie flat.
Starting the Sweater

Starting at the bottom left corner of the sweater, make a chain the width of the template, add one chain and turn. Please leave a long enough tail to sew one side together at the end. Sc to the end of the row, ch 1 and turn. Repeat until you need to start the right arm.
Arms

Instead of turning, chain the length of an arm, chain one and turn. (Make a note of how many chains you made so your other sleeve will be the same length.) Sc the chain and width of the body of the sweater. At the end, make a chain the same length as the right sleeve (making sure to include the extra stitch) and turn. Sc until you need to start the neck hole. Be sure to ch 1 and turn at the end of each row. If your arms look uneven, don't worry, that will be resolved when it gets sewn together.
Neck Hole

OK, here is where the math comes in. Count the stitches between the beginning of the arm and where you want the neck hole to start. Now subtract the number from the remaining stitches. That is the amount of chains you need to do to make sure your neck whole is in the middle of your sweater and your arms are even. Skip the same amount of stitches as your chain. Sc in the next stitch and cont. to the end of row, ch 1 and turn. Sc as many rows as you need to match the template, ch 1 and turn at the end of each row.
Sweater Back

Going by your template, sc just the width of the body of the sweater, matching the front, stopping at the sleeve, ch 1 and turn. Counting in from the other side, sc to the end of the body of the sweater stopping at the sleeve on the other side, ch 1 and turn. Sc the rest of the body. Stop at the top right corner of the template. Make sure your tail is at the bottom left. Leave enough yarn to sew the other side, cut and pull the yarn through.
Sewing Sweater Together

Fold the sweater in half, with the neck hole at the top. Using your tails, sew each side and the arms. Do not sew your arm holes, make a knot and weave in your ends. Congrats, you have a mini sweater!
(I made my own wire hangers and decorated them as desired.)
This is my first tutorial ever, so if there are any problems, please let me know!
Have fun!