$fn = 64;

// --- Parameters ---
// Diameter of the paint tubes (31mm fits standard 60ml acrylic/oil tubes)
tube_d = 31;
// Wall thickness of the holders
wall = 2.4;
// Grid columns
cols = 5;
// Grid rows
rows = 4;
// Angle of tubes for visibility and access (degrees)
angle = 45;
// Depth of the tube holder cups
depth = 40;

// --- Derived Dimensions ---
outer_d = tube_d + wall * 2;
spacing_x = outer_d + 4;
spacing_y = 45;
bp_width = (cols - 1) * spacing_x + outer_d + 8;
bp_height = (rows - 1) * spacing_y + outer_d + depth * sin(angle) + 10;
bp_thick = 4;

// --- Main Assembly ---
// Designed to print flat on its back. 
// The cups will print without supports. 
// The mounting cleats on the back will require minor supports.
union() {
    // Main body (Backplate + Cups)
    difference() {
        union() {
            // Backplate
            cube([bp_width, bp_height, bp_thick]);

            // Array of angled cups
            for (c = [0 : cols - 1]) {
                for (r = [0 : rows - 1]) {
                    x = c * spacing_x + outer_d / 2 + 4;
                    y = r * spacing_y + outer_d / 2 + 10;
                    
                    translate([x, y, bp_thick])
                        rotate([-angle, 0, 0])
                            cup();
                }
            }
        }
        
        // Trim anything that protrudes behind the backplate (Z < 0)
        translate([-10, -10, -50])
            cube([bp_width + 20, bp_height + 20, 50]);
    }

    // Mounting Cleats (ArtArsenal / French Cleat style wall hooks)
    translate([0, bp_height - 10, 0]) 
        rail_cleat(bp_width);
        
    translate([0, 40, 0]) 
        rail_cleat(bp_width);
}

// --- Modules ---

module cup() {
    difference() {
        // Outer shell
        cylinder(d=outer_d, h=depth);
        
        // Inner hole for the paint tube
        translate([0, 0, wall])
            cylinder(d=tube_d, h=depth + 1);
            
        // Front visibility and access slot
        // Placed on the +Y side, which rotates to become the top face
        translate([0, outer_d / 2, depth / 2 + 8])
            cube([tube_d * 0.6, outer_d, depth], center=true);
    }
}

module rail_cleat(w) {
    // Extension from backplate (overlaps by 1mm into backplate for a manifold union)
    translate([0, -6, -8]) 
        cube([w, 6, 9]);
        
    // Downward pointing hook body
    hull() {
        translate([0, -6, -8]) 
            cube([w, 6, 4]);
            
        translate([0, -14, -8]) 
            cube([w, 0.1, 4]);
    }
}