Buyers can aid greatly in this respect in various ways, the most important of which is to incorporate in their orders the words "substitution permitted" or "nearest size and color", which gives the companies a little latitude so that they can fill the order from stock on hand rather than waiting for it to run through the plant. Your order might happen to reach the plant just in time to be poured in your particular color and shape along with some big industrial order, in which case you would get your material within a week or so, or they might have it on the shelves already as a result of some previous over-run, but on the other hand, it could conceivably be weeks or even months before your order could be attached as a "rider"to a large commercial order for your specified color and shape. By permitting substitution of a similar color (there are probably 30 different "reds" for instance), or by allowing them to substitute a 7/8" diameter rod for a 3/4" rod in your color, the chances are nine times out of ten your order could be filled immediately from stock on hand. But if you MUST have some particular shape and color, you must be prepared for the possibility of a delay in filling your order, even in such common colors as blacks and whites.
Another way in which schools particularly can expedite their orders is by laying out their projects in such a way that they call for a dozen or more identical pieces, making it worth while to run a full mold of this size at once, instead of waiting for a commercial order to bunch it with. School projects can easily be figured out so that the orders are easy to fill, instead of being the hodge-podge they usually are.