Most of my animal blocks look great on pillows, but not all of my patterns include complete instructions for making pillow covers.
To make adapting these patterns easier, I've made a "cheat sheet" with basic guidelines for constructing 18" x 18", 20" x 20", 24" x 24", 26" x 26", and/or 16" x 26" quilted pillow covers.
This document describes the basic process of making a quilted pillow cover with a bound envelope back. You may need to do a little bit of calculating to figure out how much fabric to add to a block to make the desired size pillow front, but the document includes all of the yardages and sizes you'll need for the pillow back panels, batting, and lining for each pillow size.
When selecting a pillow form for a quilted cover, I usually go with the exact size of the cover (for instance, a 20" x 20" pillow form for a 20" x 20" pillow cover). The type of form that you use may affect what size will look best. I've found that the stiffer polyester forms sold at many craft stores tend to fit best into a quilted cover that is exactly the same size. Softer forms from stores like IKEA can be a little more flexible. For instance, I've found that the IKEA 26" x 26" pillow forms can often fit both 24" x 24" and 26" x 26" forms. Don't hesitate to mix and match forms to suit your preference for a softer or fuller pillow!
Note: The photo above shows a pillow made with my Bjorn Bear pattern. Bjorn Bear is available as a printed pattern booklet in stores worldwide, including those listed on my Stockists Page.