Hello. I also make this sort of thing to sell, but from recycled fabric and reversible. The cotton layer normally goes on the inside for comfort. I mean the saks type of thing, although I call them homes. I do cuddle bags which are very soft and homes which have a stiffened opening. The cuddle bags are easier to make, but specifically for cuddling (and they're nice to use for that!) The homes with the stiffened openings are a bit harder to make.
The major difference with mine is the recycled fabrics. So there isn't a 'range' of fabrics to choose from there's just what I happen to have at the moment.
It's very interesting to see other people talking about their stuff too, very interesting to see the variety on offer. I like the folded back cuff effect on the fleece ones, and I think the 11" x 13" is fine on the size. I know cozy cavey on ebay sells smaller ones which often don't fit fully grown piggies in so if you're thinking of getting one be careful of the size.
If you want to see what I do then I have a link on my details. I must admit I am proudest of being able to make beds/homes for anyone and anything, including hedgehogs, baby parrots, sugar gliders etc etc! Not just piggies!
Last of all, I did give a method of making a simple padded bed on a different thread in the housing section - I think it was called DIY for piggies. I'm perfectly happen to send further instructions if anyone wants them, I've been making various stuff for my piggies for years and years!
Sarah x