The foundation of all commodities futures trading is the production/supply side and purchasing/taking-delivery side. There is no market without them. You can buy and sell to your hearts content before the contract month is up, but if you can't either produce or take delivery, you have to close out your position(or buy/sell to roll to a new delivery date). Every ounce/kilo/ton/bushel/etc left gets scheduled for delivery. Every commodity trading company has employees whose sole job is to schedule the chains of buys and sells, most of which financially book-out (a buy and sell to and from the same company), but the rest are chains of buys and sells that start with production and end with physical delivery. For example, a physical chain may look like: A random silver mining company - Morgan Stanley - Merrill Lynch - JP Morgan - Koch - Cargill - A random manufacturing company that uses silver. A book-out would look like JP Morgan - Merrill Lynch - JP Morgan, or JP Morgan - Merill - Koch - JP Morgan. Every buy and sell lies somewhere on these chains. Don't confuse these with ETFs.
If you wanted to take delivery: