$fn = 64;

// --- Parameters ---
num_slots = 6;
slot_diameter = 12;
slot_spacing = 20;
opening_width = 9; // Slightly smaller than slot_diameter for a snap-in fit

holder_width = num_slots * slot_spacing;
holder_depth = 30;
holder_height = 20;

// Dovetail parameters (ArtArsenal style rail mount)
dt_base = 16;
dt_neck = 10;
dt_depth = 5;

// --- Modules ---
module dovetail() {
    linear_extrude(height = holder_height)
    polygon(points=[
        [-dt_neck/2, 0],
        [dt_neck/2, 0],
        [dt_base/2, -dt_depth],
        [-dt_base/2, -dt_depth]
    ]);
}

module brush_holder() {
    union() {
        // Main body with U-slots
        difference() {
            // Solid base block
            cube([holder_width, holder_depth, holder_height]);
            
            // Cutout slots
            for (i = [0 : num_slots - 1]) {
                slot_x = (i + 0.5) * slot_spacing;
                slot_y = holder_depth - 12; // Center of the slot
                
                // Main circular hole
                translate([slot_x, slot_y, -1])
                    cylinder(h = holder_height + 2, d = slot_diameter);
                
                // Front opening cutout
                translate([slot_x - opening_width/2, slot_y, -1])
                    cube([opening_width, holder_depth - slot_y + 2, holder_height + 2]);
            }
        }
        
        // Mounts: Two dovetails for stability on the wall rail
        translate([holder_width * 0.25, 0, 0]) dovetail();
        translate([holder_width * 0.75, 0, 0]) dovetail();
    }
}

// --- Render ---
// Centered on the X axis, back flush with Y=0
translate([-holder_width/2, 0, 0])
    brush_holder();