No longer a mystery, but still great fun to knit (the original clues are still there, but there is also a file called “consolidated” which is everything in a single file.

Designed to work with what you have - so why not take a deep dive into your stash and see what you come up with …

You can use any weight from sport to aran
you can have one difference in weight between the yarns
Contrast is really good
if one yarn is striping, handspun or variegated you’ll get extra complexity for no extra effort

you can also combine similar colours with different textures (although you will have to concentrate a bit more when knitting)

two semi-solids can be interesting

two solids can also work but will more graphic, less blended.

allow about 150m/165yds of each of the 2 yarns (you’ll probably use less, but then you’ll have a buffer)