How to build a wooden wishing well
Step 3. Space the palings
The distance of the gap between the palings is crucial to forming a good circle. In this instance, the palings are 25mm (1") thick so the gap will be 10mm (3/8"). If the palings are a different thickness, then the gaps will also need to be different. (See The Gap Equation on the next page for a detailed explanation.)
If you use palings of a different thickness, use the Gap Equation on the next page to establish the gap size. That is, divide the thickness of the paling by 2.6
Note: This gap formula will only work if the corners of the palings are square. If the corners are rounded the equation will not work.
Cross-section of the palings.
There is however, another method that does work. There is a way you can use lumber with rounded corners, as explained on page 8.