init

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "plaster_calc"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "plaster_calc"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

src/main.rs

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+use std::env;
+use std::process;
+
+const GRAMS_PER_OUNCE: f64 = 28.349523125;
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+
+    if args.len() != 2 {
+        eprintln!("Usage: {} <part_volume_cm3>", args[0]);
+        process::exit(1);
+    }
+
+    let part_volume_cm3: f64 = match args[1].parse() {
+        Ok(v) => v,
+        Err(_) => {
+            eprintln!("Error: volume must be a number");
+            process::exit(1);
+        }
+    };
+
+    println!("\n=== Full scale ({:.2}cm^3) ===", part_volume_cm3);
+    print_volume_stats(part_volume_cm3);
+
+    let scaled_volume = part_volume_cm3 / 8.0;
+    println!("\n=== 1/8 scale ({:.2}cm^3) ===", scaled_volume);
+    print_volume_stats(scaled_volume);
+}
+
+fn print_volume_stats(part_volume_cm3: f64) {
+    // about 1.5 parts water produces 2 parts mix
+    let water_volume = part_volume_cm3 * (1.5 / 2.0);
+
+    // density of water ≈ 1 g/cm^3
+    let water_mass_g = water_volume;
+
+    // 16 parts plaster : 10 parts water (by weight)
+    let plaster_mass_g = water_mass_g * (16.0 / 10.0);
+
+    let water_mass_oz = water_mass_g / GRAMS_PER_OUNCE;
+    let plaster_mass_oz = plaster_mass_g / GRAMS_PER_OUNCE;
+
+    println!("Water:   {:.2} g ({:.2} oz)", water_mass_g, water_mass_oz);
+    println!(
+        "Plaster: {:.2} g ({:.2} oz)",
+        plaster_mass_g, plaster_mass_oz
+    );
+
+    // add 10% slack
+    let water_slack_g = water_mass_g * 1.10;
+    let plaster_slack_g = plaster_mass_g * 1.10;
+
+    let water_slack_oz = water_slack_g / GRAMS_PER_OUNCE;
+    let plaster_slack_oz = plaster_slack_g / GRAMS_PER_OUNCE;
+
+    println!("With 10% slack:");
+    println!("Water:   {:.2} g ({:.2} oz)", water_slack_g, water_slack_oz);
+    println!(
+        "Plaster: {:.2} g ({:.2} oz)",
+        plaster_slack_g, plaster_slack_oz
+    );
+}