This pattern explains in detail how to create the delta symbol shape using the overlay mosaic crochet method.

It also contains charts for creating a blanket of repeating delta symbols.

The blankets shown are about 63” W x 66” L but this pattern can be worked to any size.

I used a 6.5mm hook (US size K)

I used Lion Brand Heartland Yarn (100% Acrylic)
o Color A (Deltas & Border) – about 9 skeins (2,070 yards)
o Color B (Background) – about 8 skeins (2,008 yards)

Pattern also has a link to a YouTube video tutorial.