Wrong section All of these have been suggested. 1) Paper is useless, it just burns and looks white. 2) Plastic was coded, playtested, and taken out. It broke OIL 3) Colored metal works just fine. If you're looking for sparkly things, drop water on SPNG 4) There are already 10^10^10^10 ways to kill stickman. What's the point of another?
Paper has been suggested a lot before, and it's not really useful at except burning faster, and what's the use of that when you can just use less fuel?
For plastic, see Neospector's post. Even AntB suggested it once, but it was rejected.
Gold: Yes, you're right, this has been suggested heaps of times before, and it barely has a use that can't be replaced by another element.
We already have SMKE, which is basically CO2 and that has way more uses than killing stickmen, which rules out CO.
PRO TIP: Use the searchbar to check if anyone else has suggested what you've suggested, to prevent mass flaming.