They're great fun to make and they're very versatile. I use up bits of yarn left over from other projects, also ones which are bargains in the shops and in charity shops.
The first things to do is to knit great long lengths (about 4' or longer) of about 40 stitches on large knitting needles, using thick wool. Knit enough to make it as long as you'd like (6' x 4' is a good size - or larger). Then crochet them together - it's faster than making squares.
Then I do a few rows of crochet around the edge to look pretty.
Finally finally back the rug with a piece (or patchwork of pieces) of cotton fabric, turning under the fabric edges and leaving the crochet edges with no backing (so they're thinner).
These rugs (or throws) look good draped over the sofa and are great for cuddling up in front of the TV. Some people use them as an extra rug on the bed on cold winter's nights.
For another Cumfy Rug I crocheted squares, joined them together and put a fleece backing which makes it really warm, although it is much thicker.
Here are some pics of the latest effort:
These colours were chosen to go with our old sofas but luckily they still look alright with our 'new' ones.
Needless to say, the cats love the warm softness of these rugs.
This is a few pictures of the blue Cumfy Rug:
Back, showing the blue/blue patterned lining.
Back, showing crochet edging and how lining sits just inside
If anyone wants to make one of these, there's no reason why, if they can't yet crochet, then can sew the pieces together and do some fancy knitting around the edge.