Matchlocks firearms are easy to make in terms of resources but still require some time to produce. Handgonne/handcannon is even easier to make.

Handcannon
Handgonne requires match cords or strings, gunpowder and large stone musket balls to shoot. It can be crafted using just wood (sticks or a stock) and a stone barrel without the need of creating a mechanism.

Additional context
I had the idea of needing a fire source required to shoot it, but matchlock weapons already do not need it. I still think it would be cool to make it so you need flint and steel to shoot it, or maybe you need to rightclick fire and it will shoot after a short delay.