Is it true that women have no spacial concepts? It is not, and if you are unconvinced of this falsehood by the mathematics and spatial concepts required to create a simple patchwork quilt, then consider the humble “Baby Surprise Jacket” designed by Elizabeth Zimmerman in the 1960s.
The Baby Surprise Jacket is knitted in garter stitch, the simplest of knitting stitches. By a series of increases and decreases combined with one instance of dropping stitches to be picked up later, a single knitted cloth is created. Folded origami-like it suddenly and surprisingly becomes a cardigan aka a jacket. It requires only two invisible seams across the top of the sleeves and six suitable buttons for the garment to be finished.
The instructions for this amazing and very popular design are published in “The Opinionated Knitter”, by Elizabeth Zimmerman, 2005, Schoolhouse Press on page 102.
Elizabeth Zimmerman wrote her patterns in a narrative style unlike the highly structured and standardised line by line code modern knitters are used to. It sounds like it would be easier to follow but it does require a considerable foreknowledge of knitting techniques and a familiarity with her turn of phrase to follow the instructions. This is especially true if it is the first time you have made it so, it is not for a beginning knitter. (There are however many blogs and YouTube instructions that attempt to translate her instructions with varying degrees of success.)
The Transformation
Before folding 
Front 
Back
I have long wanted to master this design and so spent some considerable time recently doing just that.
I made four altogether
Another 4 ply version 
8 ply version 
Another 8 ply version
This design is also notable for its versatility in that the size of the finished garment is determined by a combination of the weight of the yarn used, the gauge of the needle, and the tension of the knitter.
Different sizes
4 & 8 ply size comparison 
Every jacket is a different size
Although I no longer have any babies to knit for, this design is so satisfying that I’m sure I will come back to it again. I rarely short other people who are only too happy to be endowed a hand-knitted baby cardigan.