I didn't have a pattern but I do have a fleece sling that I used for sizing. It was a little tricky to make sure I sewed the pieces correctly to make it reversible but I was lucky to get it right the first time. It just took a lot more thinking than normal sewing projects!
Re: **MrsStubbs**
I've purchased things before just to use them as rough patterns. Then I return them after my project is completed.