One of the knitting techniques I really enjoy is double knitting, because every time I work in this technique I'm intrigued by the fact that the created fabric is reversible and looks beautiful from both sides since there seems to be no 'wrong side'.
A double-knit fabric is comprised of two layers of fabric worked simultaneously. It is worked in pairs of stitches, for each knit stitch worked on one side, a purl stitch is worked next for the other side. This technique creates a thick fabric, which seems to have two right sides, because the wrong sides are facing each other in the middle of the fabric.
The technique can be worked with just one colour for example for an extra thick scarf, but more often two colours are used to form motifs. The fun effect is, that the motif appears on the second side as a negative image with reversed colours. In the picture below you see the 'right side' with white lines on black and the 'wrong side' with black lines on white.
The first pattern in double knitting technique I published a while ago was the Rhomboid Cowl. Worked in a classic monochrome geometric pattern, enhanced with small details in a contrast colour as the eye-catching feature. The red 'line' above is the cast-on edge, done in the third colour; the optional contrast coloured diamond (in red in the picture) was added at random using duplicate stitch.
I've recently revised the pattern and added detailed written instructions for everyone who'd like to give double knitting a try, but is hesitant to work from charts. The pattern is available from my Ravelry store, here: Rhomboid Cowl.