Chapter 2, Misha 3, 4
If one sets aside more money than he needs to pay his annual half-shekel obligation, what should be done with the surplus? Is it consecrated, or is it his? Why do we get a different result if he saves up one coin at a time vs. grabbing a stack of coins? Why is the result different if the money is set aside to purchase a sin-offering? Why does the Torah specify a half-shekel as the annual obligation when the Temple is standing? Can money set aside for one kind of offering be used for a different kind?