Step 5: stack your flat stone to a height of about 1.5 feet. The key to a good dry stack is taking the time to piece the rocks together. Try to lay a flat edge next to a flat edge, if one rock has a curve find another that compliments the curve so they lock together. It's basically a huge game of adult Legos. A 3 pound stone hammer comes in handy as well. You can shape some of your rocks with it to get a better fit. A few whacks in the same spot can create a nice smooth edge or knock off a pesky jag in a rock so it fits better. Try to keep the rounded edges outward so you create a nice circular appearance on the exterior. I also tried to use pieces with interesting colors or features on the exterior of the wall. Finally, a dry stack wall will have pieces that just don't lay in tightly. Try to avoid this, but if you can't, use some of the smaller stone shards as shims, or wedges, between the loose pieces to secure them. As the wall settles, these pieces will fall in and become tighter. And remember: gaps, in moderation, are good! They allow air into your fire pit which will keep it roaring on those cool fall nights!