I have tried to cast a little spear point out of bronze in a homemade clay mold and it worked decently well except the fact that I squished the mold a little and so I couldn't get the full length of it. I have an electric furnace for that, a little 2 kilo one, I've tried melting a mix of brass and bronze in a coal forge (make sure to add flux if you are melting brass because the zinc wants to burn off) but I was running out of coal so I was rushing and didn't get it to all melt . Now for your project if you want to still cast some bronze for your project I would cast a large flat circular ingot and then forge it out, it is very hard to cas something that is very thin so even in the bronze age they would cast a smaller thicker partially formed blank and hammer that to shape,if you want to research that look up how they made Corinthian helmets.also when you forge it remember that bronze has a lower melting point than iron or steel so you want to keep it below a yellow heat at all times(you could melt some of it to see the exact heat at which it is).