2. Make sure the open end of the base is facing downward. Then, fold one of the sides into the middle, like so.
3. Use your finger to slightly open the fold.
4. Make a squash fold.
5. Repeat Steps 2 – 4 on the remaining three flaps of the square base.
6. Fold the sides of the top layer of paper inward, like so. Then, undo these folds.
7. Insert a finger into the space in the middle of the frog base and carefully begin to move it upward. This step is similar to completing Steps 5 and 6 of the crane base.
After you complete Step 7, your frog base should look like this. (Tip: It’s okay to be a little bit forcefully with the paper when trying to smooth out the top part of the interior diamond. I’ve also found that using my fingernail to strongly crease the upper corners of the interior diamond really helps to shape it correctly.)
8. Repeat Steps 6 and 7 on the remaining three squash-folded layers of paper, and your frog base is complete!