Designing is not as hard as you might think, especially when you use your resources!
What I did is to use a pattern generator
(uses your measurements) for a top-down raglan sleeve in a cardigan form, then combined it with a stitch that I liked from a stitchionary. This one is called a vine stitch, I believe.
I broke at the waistline with a little ribbing in a smaller needle size, then went back to the original stitch pattern (and the original needle size) for a few more inches. I ended with an inch of simple seed stitch to finish. The buttonhole and buttonband I also did in seed stitch.
For the sleeves, I continued with my vine stitch for a little while, and broke with some ribbing (smaller needle) down to the elbow. I added a seed stitch neckband. And I was done!
Because the pattern generator uses your measurements, all garments produced by this method fit perfectly. No adjusting necessary. And it works for any size!
So, now you have your "pattern" for making anything you want. Just add ingenuity and creativity and stir. Bake for an hour and serve.