1. The crane base is actually developed from the square base. When your square base is finished, it should look like this. Make sure the open corner is facing you.
2. Fold the sides of the top layer into the center, like so.
3. Repeat Step 2 on the reverse side.
4. Fold the top triangle down. (I usually also fold it the same way on the reverse side to make a better crease.)
5. Unfold the paper back to the square base. There should now be three very pronounced crease lines on the paper. As shown, insert a finger into the opening at the bottom. Gently, begin to pull the bottom of the paper up toward the top.
6. Continue folding the bottom of the paper upwards, and flatten out one side at a time as you do so. (Tip: I’ve found that this step is much easier to accomplish if you do it while holding the paper in mid-air, rather than trying to keep it flat on a table.)
7. Flatten the other side of the paper so the paper looks like this. Repeat this step on the reverse side, and ta-da! You’ve made the crane base!