I found a jumper with a two-toned effect that I wanted to replicate. I tried six different ways of combing two industrial yarns to create this effect. The sixth way was the best.
If you are machine knitting with fine yarn a twisting stack that enables you to loosely twist up 2 or 3 strands of yarn is a very useful item to buy or make.
Wool winders and twisting stacks can make it easier for a machine knitter to knit with multiple strands of fine yarn.
Yarn can be expensive to buy so it is important to find a source of inexpensive yarn that you can use for practice.