> ((2.17-.25)% per 1.7 mm thick) this works out to 88.6 mm for 100% coverage or around 3.5 inches. 2.17% is when only one side is shielded: "it can be extrapo

> ((2.17-.25)% per 1.7 mm thick) this works out to 88.6 mm for 100% coverage or around 3.5 inches. 2.17% is when only one side is shielded: "it can be extrapolated that the biomass would reduce total radiation levels (of the measured spectrum) by 4.34±0.5% were it fully surrounding an object" But your assumption that this thing scale linearly is far from reality, see for example their estimate for Mars: "In a case study we estimated that a ~ 2.3 m layer of melanized fungal biomass (8.6% [wmelanin/wCWW] melanin-content) would be needed to lower Martian radiation levels to those on Earth (from 234 mSv/a to 6.2 mSv/a [6, 7, 53])" ISS is at apporximately 144 mSv/a.