The cubit is the measure of the arm from the elbow to the tip of the middle finger, which on the average man is approximately 18 inches. A span is the distance between the thumb and the little finger when they are stretched apart which is generally about 1/2 a cubit or approximately 9 inches. A hand is the distance between the little finger and the thumb with the hand closed.
It is reasonable to assume that a 10 cubit molten metal bowl would have a thickness of about a hand, which would be the perfect measuring distance if you were going to build a mold.
So I am simply using the measurment standards in existence at the time of the building of Solomon's Temple. And since a cubit is not an exact measurement but is an approximate measurement, how many cubits would you have if if you rounded the 29.85 cubits to the nearest cubit?
When you know what you want as a result, it's not hard to come up with a mechanism. In science, we call it handwaving.
Pi is three, or four, or whatever.