Fwiw. Jax got me wondering about Iron. Did the maths, scratched my head. wth-eck? thought some might find it interesting...
I've mined approx 16,000+ Stone this playthrough. Maybe only 10 Boulders? Majority was below ground. Bought Mother Lode & Miner 69er as early as possible. Total Iron Ore mined is about ~1,000. So cooked up would be 5,000 Iron or 500 Forged Iron. Made an axe, pick, hoe & hammer so used 20+20+16+12=68. Could build Two rows of Metal Spikes for a 7x7 for 288 Forged Iron. Three rows would take 480.
Upgrading Wood w Iron or making Scrap Frames in Forge is similar Iron cost wise. Upgrading Wood costs ~8 wood then Iron costs 12, 40 & 40. Scrap Frames cost 15 Iron in Forge then 40 & 40. So using 92 Iron as an upgrade cost the 5,000 Iron I could have would only upgrade 54 blocks. Those blocks would have 2,000 total hps. (2 'layers' of 1,000 hps each).
Looking at Flagstone to Cobblestone. 1 Stone + 1 Clay/dirt = 1 Cobblestone. 1 Flagstone block takes 4 Cobb. Upgrading Flag to Cobb take 10 Cobblestone. Cobb blocks have 1,500 hps total; no degrade path so broken = gone.
Say I'd used half the time mining stone to dig dirt. (know it's not that but as an example) 8,000 Stone & Dirt so 8k Cobblestone Rocks. Need 14 to make then upgrade so could build 571 Cobblestone blocks.
Currently the next upgrade for either top-lvl-Scrap-Iron or Cobblestone is Concrete.
Definately suprised me. Iron felt pretty scarce but.., wowsa. Definately not an early game building material for me
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@canadianbluebeer, good additional info. Hadn't realized the per shot degradation was >1, good to know!