$fn = 64;

// --- Parameters ---
width = 50;          // Total width of the stand
depth = 120;         // Projection distance from the wall
height = 140;        // Height of the wall plate
wall_t = 6;          // Thickness of the outer shell and structural ribs
lip_h = 25;          // Height of the front retaining lip
canvas_gap = 35;     // Gap between front lip and backrest for canvas thickness

hook_d = 8;          // Depth of the wall rail hook
hook_drop = 12;      // Drop height of the wall rail hook
bumper_h = 15;       // Height of the bottom wall standoff

// Calculated start point for the angled backrest
rest_x = depth - wall_t - canvas_gap;

module profile() {
    // Round the sharp convex outer edges slightly for a better feel
    offset(r=1) offset(r=-1)
    union() {
        // Main body wedge and canvas rest
        polygon([
            [0, 0],
            [depth, 0],
            [depth, lip_h],
            [depth - wall_t, lip_h],
            [depth - wall_t, wall_t],
            [rest_x, wall_t],
            [wall_t, height],
            [0, height]
        ]);

        // Top wall rail hook (ArtArsenal / French cleat style)
        polygon([
            [0, height],
            [-hook_d, height],
            [-hook_d, height - hook_drop],
            [0, height - hook_drop + hook_d]
        ]);

        // Bottom wall bumper to keep the stand vertical
        polygon([
            [0, 0],
            [-hook_d, 0],
            [-hook_d, bumper_h],
            [0, bumper_h + hook_d]
        ]);
    }
}

module hollow_cutout() {
    // Inner triangular cutout to hollow the body, leaving sturdy structural ribs
    polygon([
        [wall_t, wall_t],
        [rest_x - wall_t * 1.5, wall_t],
        [wall_t, height - wall_t * 2.5]
    ]);
}

// --- Main Object ---
// The part is generated lying flat on its side.
// This is the optimal orientation for 3D printing (no supports needed, maximum hook strength).
difference() {
    // Solid outer body
    linear_extrude(width)
        profile();

    // Hollow center
    translate([0, 0, wall_t])
        linear_extrude(width - 2 * wall_t)
            hollow_cutout();
}