8 rockets to destroy a Sheet Metal Wall. That's 11,200 sulfur in raw materials.
4 C4 charges to break a Sheet Metal Wall — roughly 8,800 sulfur plus metal fragments and tech trash.
23 satchels to destroy a Sheet Metal Wall in Rust. Satchels have the best damage-per-sulfur ratio on soft sides.
The cheapest explosive option for a Sheet Metal Wall is 112× Beancan Grenade at roughly 6,720 sulfur.