$fn=64;

// --- Parametric Variables ---
// Organizer grid configuration
rows = 2;                  // 2 rows: one for nuts, one for matching washers
num_sizes = 5;             // 5 size categories (e.g., M3, M4, M5, M6, M8)

// Compartment dimensions
base_width = 20;           // Width of the smallest compartment (mm)
width_increment = 6;       // Width increase for each subsequent size (mm)
comp_length = 45;          // Front-to-back length of each compartment (mm)
comp_height = 18;          // Inside depth (mm)

// Structural dimensions
wall = 2.5;                // Wall thickness between compartments (mm)
floor_thick = 2;           // Base floor thickness (mm)
scoop_depth = 18;          // Depth of the sloped front scoop for easy retrieval (mm)

// --- Calculated Dimensions ---
// Calculate overall dimensions based on the arithmetic progression of widths
total_width = (num_sizes * base_width) + 
              (((num_sizes - 1) * num_sizes / 2) * width_increment) + 
              ((num_sizes + 1) * wall);
total_length = (rows * comp_length) + ((rows + 1) * wall);
total_height = comp_height + floor_thick;

// Helper functions for positioning
function comp_w(col) = base_width + (col * width_increment);

function x_offset(col) = 
    col == 0 ? wall : 
    wall + (col * base_width) + (((col - 1) * col / 2) * width_increment) + (col * wall);

// --- Main Geometry ---
difference() {
    // Main solid block
    cube([total_width, total_length, total_height]);
    
    // Subtract all compartments
    for (r = [0 : rows - 1]) {
        for (c = [0 : num_sizes - 1]) {
            
            w = comp_w(c);
            x = x_offset(c);
            y = wall + r * (comp_length + wall);
            z = floor_thick;
            
            translate([x, y, z]) {
                // Compartment with front scoop for easy part retrieval
                hull() {
                    // Bottom flat area (starts after the scoop)
                    translate([0, scoop_depth, 0])
                        cube([w, comp_length - scoop_depth, 0.01]);
                    
                    // Top opening (extends slightly above for clean manifold subtraction)
                    translate([0, 0, comp_height])
                        cube([w, comp_length, 1]);
                }
            }
        }
    }
}