This is a great project for learning the basics of mosaic knitting.
I wanted a dense fabric for these trivets so chose a worsted weight yarn and knit it on a smaller needle than usual to create a nice sturdy fabric appropriate for the use of the finished project.

Since this isn’t a fitted garment, you have lots of flexibility in what yarn and needle size you choose! Just keep in mind that going to a larger yarn or using a larger needle will make the trivet larger - which you might prefer for larger dishes - and going to a smaller yarn and smaller needles will do the opposite.

The pattern shows off best with a light and a dark color. No reason you couldn’t do one solid and 1 long repeat (like Noro Kureyon or Silk Garden) for a different effect. You could even work 2 different colors of Kureyon or Silk Gardens for an even more varied effect. If you choose to do this, keep in mind that the pattern will show off best if you choose colors from opposite sides of the color wheel - DON“T try to “match” your colors or you will totally lose the pattern! You need contrast in value (light and dark) or colors (blues and oranges or reds and greens or purples and yellows, etc).