Unfortunately the only place I was able to find them was Amazon.

https://a.co/d/c7XdyEn

I found a bulkhead fitting that would fit through the barrel bung on mine. There is a string trick to thread it into place; but I just kinda shook the barrel a bit and it fell into place.

Also make sure you are well covered to avoid burns from weld spatter.

And sunburn. First time I played around with welding I didn’t get any weld splatter, but just about 30 seconds to a minute of welding in short sleeves was enough to sunburn (er, I guess weldburn?) my arms. That light’s intense.