$fn = 64;

// --- Parameters ---
brush_diameter = 14;     // Diameter of the top holes for brush handles
recess_diameter = 10;    // Diameter of the bottom recesses to hold brush tips
rows = 2;                // Number of rows
cols = 6;                // Number of columns (2 x 6 = 12 brushes)
spacing = 20;            // Distance between hole centers
margin = 15;             // Margin from the outer edge to the first hole center
holder_height = 75;      // Overall height of the holder
wall = 3;                // Thickness of the outer walls
bottom_thick = 6;        // Thickness of the bottom base
top_thick = 3;           // Thickness of the top plate

// --- Calculated Dimensions ---
width = (cols - 1) * spacing + 2 * margin;
depth = (rows - 1) * spacing + 2 * margin;

// --- Main Geometry ---
difference() {
    // Main outer body
    cube([width, depth, holder_height]);
    
    // Hollow interior to save filament (creates a self-supporting box)
    translate([wall, wall, bottom_thick])
        cube([width - 2 * wall, depth - 2 * wall, holder_height - bottom_thick - top_thick]);
        
    // Top holes for brushes
    for(r = [0 : rows - 1]) {
        for(c = [0 : cols - 1]) {
            translate([margin + c * spacing, margin + r * spacing, holder_height - top_thick - 1])
                cylinder(h = top_thick + 2, d = brush_diameter);
        }
    }
    
    // Bottom recesses to prevent brushes from sliding (3mm deep)
    for(r = [0 : rows - 1]) {
        for(c = [0 : cols - 1]) {
            translate([margin + c * spacing, margin + r * spacing, bottom_thick - 3])
                cylinder(h = 4, d = recess_diameter);
        }
    }
}