My patterns will "work" with any fabric in so far as you will be able to get a finished product, but it may not look like the example shown. For this Loch Ness pattern in particular, if you use a fabric like felt that does not have any stretch, the neck and tail will be thinner than shown and, depending on the size, may be very difficult to turn right side out. Other common issues that come up when a non-stretch fabric is used include puckering and rippling on the seams.