I tried to come up with a molten metal-like texture for the lava3 texture slot, to maybe be used in foundry/heavy industrial themed maps.
This was done with a lot of layering around with Gimp's Difference clouds and other things.
To use this texture in a map, just change the value "Texture lava3" to "Textures/lava3.jpg" on your map's cfg file (see screenshot 3).
I hope it's useful for everyone!
Might still need some tweaking on the color, but we'll see.