$fn = 64;

// --- Parameters ---

// Outer radius of the tray (center to corner)
tray_radius = 90;       

// Total height of the tray
tray_height = 35;       

// Thickness of the outer walls
wall_thickness = 4;     

// Thickness of the bottom base (felt is glued on top of this flat surface)
base_thickness = 3;     

// Radius of the rounded corners
corner_radius = 8;      

// Number of sides (8 = octagon, 6 = hexagon)
num_sides = 8;          


// --- Main Model ---

difference() {
    // Outer shell
    tray_profile(tray_radius, tray_height, corner_radius);
    
    // Inner hollow area for rolling
    // Z-translation leaves the base intact, Z-height + 1 ensures a clean manifold cut at the top
    translate([0, 0, base_thickness])
        tray_profile(
            r = tray_radius - wall_thickness, 
            h = tray_height + 1, 
            cr = max(0.1, corner_radius - wall_thickness)
        );
}


// --- Modules ---

// Generates a rounded polygonal profile using a hull of cylinders
module tray_profile(r, h, cr) {
    hull() {
        for(i = [0 : num_sides - 1]) {
            rotate([0, 0, i * (360 / num_sides)])
                translate([r - cr, 0, 0])
                    cylinder(r = cr, h = h);
        }
    }
}