$fn = 64;

// --- Parameters ---

// Brush Organization
num_slots = 12;         // Number of brush slots
hole_dia = 12;          // Diameter of the brush holes
slot_opening = 9;       // Width of the front slot opening (smaller than hole_dia for a snap-fit)
hole_spacing = 16;      // Distance between hole centers
margin = 16;            // Space on the left and right edges

// Main Body Dimensions
body_depth = 35;        // Depth of the holder
body_height = 20;       // Height/thickness of the holder
body_width = (num_slots - 1) * hole_spacing + 2 * margin;

// Dovetail Mount (ArtArsenal / standard wall rail)
dovetail_depth = 5;       // How far the dovetail sticks out the back
dovetail_width_top = 18;  // Widest part of the dovetail (furthest from body)
dovetail_width_base = 12; // Narrowest part of the dovetail (at the body)

// --- Calculated Variables ---
d_center = body_height / 2;
z_top = d_center + dovetail_width_base / 2;
z_bot = d_center - dovetail_width_base / 2;
tip_top = d_center + dovetail_width_top / 2;
tip_bot = d_center - dovetail_width_top / 2;

// --- Main Geometry ---
difference() {
    // Main Body with Dovetail Profile
    // Using multmatrix to map 2D [Depth, Height] extrusion to 3D [Width, Depth, Height]
    multmatrix([
        [0, 0, 1, 0], // Map Extrusion Z to Final X (Width)
        [1, 0, 0, 0], // Map Polygon X to Final Y (Depth)
        [0, 1, 0, 0], // Map Polygon Y to Final Z (Height)
        [0, 0, 0, 1]
    ])
    linear_extrude(height = body_width)
    polygon([
        [0, 0],                               // Bottom-back of body
        [body_depth, 0],                      // Bottom-front of body
        [body_depth, body_height],            // Top-front of body
        [0, body_height],                     // Top-back of body
        [0, z_top],                           // Dovetail start top
        [-dovetail_depth, tip_top],           // Dovetail outer top
        [-dovetail_depth, tip_bot],           // Dovetail outer bottom
        [0, z_bot]                            // Dovetail start bottom
    ]);

    // Brush Slots (Holes + Front Openings)
    for (i = [0 : num_slots - 1]) {
        x_pos = margin + i * hole_spacing;
        y_pos = body_depth * 0.55; // Positioned slightly forward of center

        // Cylindrical Hole
        translate([x_pos, y_pos, -1])
            cylinder(h = body_height + 2, d = hole_dia);

        // Front Slot Cutout
        translate([x_pos - slot_opening / 2, y_pos, -1])
            cube([slot_opening, body_depth, body_height + 2]);
    }
}