$fn = 64;

// --- Parameters ---
stand_width = 60;     // Width of the stand
slot_depth = 25;      // Depth of the canvas slot (fits standard canvas frames)
thickness = 8;        // Thickness of the walls and base
lip_height = 20;      // Height of the front retaining lip
back_height = 110;    // Total height of the backrest
tilt_angle = 15;      // Backward tilt angle of the canvas (degrees)
min_base_length = 95; // Minimum depth of the base for stability

// --- Calculations ---
// Calculate the coordinates for the angled backrest
L = back_height - thickness;
p5_x = thickness + slot_depth;
p5_y = thickness;

p4_x = p5_x + L * sin(tilt_angle);
p4_y = p5_y + L * cos(tilt_angle);

p3_x = p4_x + thickness * cos(tilt_angle);
p3_y = p4_y - thickness * sin(tilt_angle);

// Ensure the base is always long enough to support the angled back
base_length = max(min_base_length, p3_x + 15);

// --- Geometry ---
// Extruding the 2D profile. 
// Note: It is generated on its side, which is the optimal orientation 
// for 3D printing without supports and for maximum layer strength.
linear_extrude(height = stand_width, convexity = 3) {
    polygon(points=[
        [0, 0],                         // Bottom front
        [base_length, 0],               // Bottom back
        [base_length, thickness],       // Top back of base
        [p3_x, p3_y],                   // Top back of backrest
        [p4_x, p4_y],                   // Top front of backrest
        [p5_x, p5_y],                   // Bottom front of backrest (back of slot)
        [thickness, thickness],         // Front of slot (back of lip)
        [thickness, lip_height],        // Top back of lip
        [0, lip_height]                 // Top front of lip
    ]);
}