So i was doing some crafting and had to melt some notches into a plastic- it wasnt properly ventilated but i only melted a very small bit of plastic. i was googling it and it said that it was very toxic- will this hour exposure cause me any health?

No, you're fine. We are exposed to small doses of toxins every single day in the environment, but our body has ways to reduce the negative effects within our bodies.

Burning plastics produce airborne hydrocarbons which are directly irritating to the airways and the lungs. Over time, if large amounts are inhaled, they can have devastating toxic effects; especially when the fire involves multiple materials. This is what happened to vets who tended the burn pits in Iraq. Thankfully your exposure was not significant and you've learned the importance of ventilation