diff --git a/src/tools/boxcount.rs b/src/tools/boxcount.rs
index b43b2f0..865f3bd 100644
--- a/src/tools/boxcount.rs
+++ b/src/tools/boxcount.rs
@@ -4,6 +4,7 @@ use bevy::tasks::ParallelSlice;
 use crate::system::spaces::square_grid::{Grid2D, Grid3D};
 use itertools::{Itertools, MinMaxResult};
 use clap::Parser;
+use serde::Serialize;
 use crate::BoxCountCli;
 use crate::cli::cli::OutputFormat;
 use crate::system::{GriddedPosition, Position};
@@ -15,30 +16,30 @@ fn bb(data: &Vec<Grid2D>) -> ((i32, i32), (i32, i32)) {
         .iter().minmax_by(|a, b| a.x.cmp(&b.x));
 
     let y = data
-        .iter().minmax_by(|a, b| a.x.cmp(&b.x));
+        .iter().minmax_by(|a, b| a.y.cmp(&b.y));
 
     match (x, y) {
         (MinMaxResult::MinMax(min_x, max_x), MinMaxResult::MinMax(min_y, max_y)) => {
             ((min_x.x, min_y.y), (max_x.x, max_y.y))
-        },
+        }
 
         _ => panic!("Cannot determine bounding box")
     }
 }
 
-fn box_count_2d(data: &Vec<Grid2D>, box_number: u32) -> usize {
-    let n = data.len();
-    let ((x_min, x_max), (y_min, y_max)) = bb(data);
-
+fn box_count_2d(data: &Vec<Grid2D>, box_number: u32) -> (f64, usize) {
+    let ((x_min, y_min), (x_max, y_max)) = bb(data);
     let x_range = (x_max - x_min) as f64;
     let y_range = (y_max - y_min) as f64;
 
     let w: f64 = x_range / (box_number as f64);
 
-    data.iter()
-        .map(|Grid2D { x, y }| [((x - x_min) as f64 / w) as u32, ((y - y_min) as f64 / w) as u32])
+    let boxes_occupied = data.iter()
+        .map(|Grid2D { x, y }| [((x - x_min) as f64 / w) as i32, ((y - y_min) as f64 / w) as i32])
         .unique()
-        .count()
+        .count();
+
+    (w, boxes_occupied)
 }
 
 fn box_count_3d(data: &Vec<Grid3D>, size: u32) -> usize {
@@ -110,6 +111,25 @@ fn box_count_nd<const N: usize>(data: &Vec<[f32; N]>, size: u32) -> usize {
         .count();
 }
 
-pub fn main(cli: &BoxCountCli) {
-    let particles = read(&cli.path, cli.format);
+#[derive(Serialize)]
+struct FDRow {
+    w: f64,
+    n_occupied: usize,
+}
+
+pub(crate) fn main(cli: &BoxCountCli) {
+    let particles: Vec<Grid2D> = read(&cli.path, cli.format);
+    let n_particles = dbg!(particles.len());
+    let box_side_counts = 1..500;
+
+    let mut writer = csv::Writer::from_path(&cli.output)
+        .expect("Unable to create csv");
+
+    box_side_counts
+        .map(|box_side_count| box_count_2d(&particles, box_side_count))
+        // .filter(|(w, n_occupied)| *n_occupied < n_particles) // Remove saturated values
+        .map(|(w, n_occupied)| FDRow { w, n_occupied })
+        .for_each(|row| writer.serialize(row).expect("Failed to write row"));
+
+    writer.flush().unwrap();
 }
diff --git a/src/tools/mod.rs b/src/tools/mod.rs
index b44669b..34a2ec7 100644
--- a/src/tools/mod.rs
+++ b/src/tools/mod.rs
@@ -1,3 +1,4 @@
+use std::fs::File;
 use std::path::Path;
 use serde::de::DeserializeOwned;
 use crate::cli::cli::OutputFormat;
diff --git a/src/tools/render.rs b/src/tools/render.rs
index f8b5486..bf9df85 100644
--- a/src/tools/render.rs
+++ b/src/tools/render.rs
@@ -12,8 +12,10 @@ use serde::de::DeserializeOwned;
 use serde::Deserialize;
 use svg::Node;
 use svg::node::element::Rectangle;
+use crate::RenderCli;
 use crate::system::Position;
 use crate::system::spaces::hexagonal::HexPosition;
+use crate::tools::read;
 
 #[derive(Debug, Parser)]
 struct Args {
@@ -60,30 +62,10 @@ impl ToSvg for HexPosition {
     }
 }
 
-fn read_json<T: Position>(args: &Args) -> Vec<T> where T: DeserializeOwned {
-    serde_json::from_reader::<_, Vec<HistoryLine<T>>>(File::open(&args.path).expect("Failed to open file"))
-        .expect("Failed to read json")
-        .iter()
-        .map(|l| (l.position.clone()))
-        .collect::<Vec<_>>()
-}
+pub(crate) fn main(args: &RenderCli) {
+    let positions: Vec<Grid2D> = read::<Grid2D>(&args.path, args.format);
 
-fn read_csv<T: Position>(args: &Args) -> Vec<T> where T: DeserializeOwned {
-    csv::Reader::from_path(&args.path).expect("Failed to read positions csv").deserialize::<T>()
-        .collect::<Result<Vec<T>, _>>()
-        .unwrap()
-}
-
-fn main() {
-    let args = Args::parse();
-    dbg!(&args);
-
-    let positions: Vec<Grid2D> = match args.format {
-        OutputFormat::FullDataJson => read_json::<Grid2D>(&args),
-        OutputFormat::Positions => read_csv::<Grid2D>(&args),
-    };
-
-    let size: i32 = 800;
+    let size: i32 = args.image_size as i32;
     let max_x = positions.iter().max_by(|a, b| a.x.abs().cmp(&b.x.abs())).unwrap().x.abs();
     let max_y = positions.iter().max_by(|a, b| a.y.abs().cmp(&b.y.abs())).unwrap().y.abs();
     let max_size = max_x.max(max_y) * size;
@@ -105,5 +87,5 @@ fn main() {
         svg.append(position.to_svg(size));
     }
 
-    svg::write(File::create(args.output).unwrap(), &svg).unwrap();
+    svg::write(File::create(&args.output).unwrap(), &svg).unwrap();
 }
diff --git a/src/tools_cli.rs b/src/tools_cli.rs
index 2b84683..1417d47 100644
--- a/src/tools_cli.rs
+++ b/src/tools_cli.rs
@@ -2,7 +2,7 @@
 #![feature(let_chains)]
 
 use std::fs::File;
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 use anyhow::Context;
 use crate::cli::cli::OutputFormat;
 use crate::system::model::HistoryLine;
@@ -25,9 +25,24 @@ enum ToolsCli {
     BoxCount(BoxCountCli)
 }
 
+#[derive(clap::ValueEnum, Clone, Debug, Copy)]
+enum Space {
+    Grid2D,
+}
+
 #[derive(Debug, Args)]
 struct RenderCli {
+    #[arg(value_enum, short, long, default_value_t = OutputFormat::Positions)]
+    format: OutputFormat,
 
+    #[arg(value_enum, short, long, default_value_t = Space::Grid2D)]
+    space: Space,
+
+    path: PathBuf,
+    output: PathBuf,
+
+    #[arg(short, long, default_value_t = 800)]
+    image_size: u32,
 }
 
 #[derive(Debug, Args)]
@@ -35,6 +50,7 @@ struct BoxCountCli {
     #[arg(value_enum, short, long, default_value_t = OutputFormat::Positions)]
     format: OutputFormat,
     path: PathBuf,
+    output: PathBuf,
 }
 
 fn main() {
@@ -42,7 +58,7 @@ fn main() {
     dbg!(&args);
 
     match args {
-        ToolsCli::Render(_) => {}
+        ToolsCli::Render(cli) => tools::render::main(&cli),
         ToolsCli::BoxCount(cli) => tools::boxcount::main(&cli),
     }
 }