There is a glitch about the smelter. Whenever I smelt something, the smelter ALWAYS takes two pieces of stuff. If I smelt three pieces of copper at once, I get the three bars. However, I keep one of the ores. If I put in 10 ores, it makes 10 bars, but there's still 8 ores inside. Same thing happens if I smelt some bronze. However, I keep all of the bars. Could you please patch in the next update? Or at least tell me if this is a feature or not?