I did an octagonal Stack and Whack top years ago, and am making some hexagons for a current project (actually I made octagons first but wanted the more walnut shape of the hexes). Personally, I like to keep some of the fabric whole for the borders.
Chose something with a fairly large repeat (12" minimum) and get enough yardage! It takes a lot of yardage but doesn't have to be fabric wasteful, just that I'm not used to making most of a quilt from one fabric.
I've seen people who spent hours and hours on their projects only to have their work disappear because the print was just too tiny to start with. Some people carefully cut out their pieces individually, I cut identical segments (so 6 or 8 pieces) and stack them carefully matching the patterns into half (so 3 or 4) and baste the fabrics together about every 2 inches in both directions. Then I cut two identical pieces which gives me all the units needed, the basting keeps them together and is minor to take out (hint: use a high contrast thread). Depending on the fabric, I might draw a temporary line on my template to help line up the pieces, but again, I only cut twice for each block so I can usually place it accurately.
Warning about animals, you will always end up with rear ends. Now, that can be funny or not what you had in mind...
So the pictures are a stack and whack using only 3 yards or so of fabric and alternate blocks, and my octagons that just aren't what I wanted...