I wanted to make Red, Blue, and Green flames for my fire breathing dragon mask. This is how I did the Green.

Links to related projects:

Red Fire: https://www.instructables.com/id/How-to-Make-Red-F...

Blue Fire: https://www.instructables.com/id/How-to-Make-Blue-...

Fire Breathing Dragon Mask: https://www.instructables.com/id/How-to-Build-a-Fi...

Step 1: Materials Required

Methanol, and either Copper sulphate, or Boric Acid.

You must use Methanol, or ethanol, because they burn with an invisible flame. If you use another fuel, they usually burn yellow, and will not give as clear and vivid colours.

Methanol is adsorbed through the skin. It damages the liver, and if you ingest 50ml or so, you can suffer from blindness which could be permanent. A cure for methanol poisoning is ethanol. But it's best to give your liver a rest and avoid the methanol in the first place.

Copper sulphate is corrosive, as is boric acid. Boric acid is used as rat poison. Best to avoid eating it. I believe it works by thinning the blood to lethal levels. You have to eat more than a sprinkle, to kill yourself, but caution should be taken.

Step 2: Mixing Them Together

A stir plate isn't necessary, but an erlenmeyer flask and a stir bar will make life easier on you. I'd suggest a 500ml flask, My 1L is too big really. 250ml is probably too small for this: https://www.amazon.co.uk/Academy-Measuring-Molecul...

Stir bars are pretty cheap: https://www.amazon.co.uk/AJSR-magnetic-stirrer-mix...

You can easily make one out of a pc fan and two magnets.Instructions on how to make a stir plate:https://www.instructables.com/id/Stir-Plate-From-Co...

There are plenty of other instructables on this too. I might do my own.

The copper sulphate isn't as vivid as the boric acid. The boric acid is the real winner. it dissolves readily in room temperature methanol too. You don't want to saturate it, because this could lead to precipitation. This means it comes out of solution, and causes problems with your system. I recommend mixing at the lowest temperature it will be stored, or used at. And once it is saturated, filter out the remaining solids, then top up with a splash of extra methanol. Just to ensure it stays in solution.