Take a big bag and fill it with a bunch of leftover yarn that looks good together.
Using a large hook (size M or N) chain 104
Using two strands of yarn
Crochet first row in single crochet, ch 1 turn
next Row in double crochet chain 2 turn
then randomly doing either a single crochet or a double crochet row until you get the blanket the size you like.
End with a single crochet row.
I would tie a color on when I ran out of one or got tired of using the color, then I would use it later in the blanket.
Or just make a ton of magic balls and go for it.
I love making these type of blankets.
They are warm and cozy in the winter.
They also make great gifts and they use up all those little balls of yarn that you have from other projects