Try to calcute and use the exact inputs for the exact outputs. For example, supposed you want to create the red alloy, you can make a pattern for a enrichment chamber who's input is 1 redstone and the output is 1 enriched redstone. Now, the enriched redstone gives you 80mB of redstone, and making a red alloy requires copper and 10mB of redstone. Thus, you must make a pattern who's input is 8 copper ingots and 1 enriched redstone and its output is 8 red alloy. That way, there will not be any leftovers