$fn=64;

// Riser dimensions
width = 50;
depth = 50;
height = 50;
wall_thickness = 3;

// Interlock dimensions
peg_radius = 2.4;
peg_height = 3.5;
hole_radius = 2.6;
hole_depth = 4;
peg_offset = 16;
pillar_radius = 7;

// Arch cutout module for material savings and aesthetics
module arch_cutout(w, h, t) {
    union() {
        translate([-w/2, -t/2, -1])
            cube([w, t, h - w/2 + 1]);
        translate([0, -t/2, h - w/2])
            rotate([-90, 0, 0])
                cylinder(r=w/2, h=t);
    }
}

module figure_stage_riser() {
    union() {
        // Main body and cutouts
        difference() {
            // Outer shell
            translate([-width/2, -depth/2, 0])
                cube([width, depth, height]);

            // Inner cavity
            translate([-(width-wall_thickness*2)/2, -(depth-wall_thickness*2)/2, -0.1])
                cube([width-wall_thickness*2, depth-wall_thickness*2, height-wall_thickness+0.1]);
                
            // Side arch cutouts
            arch_cutout(16, 38, depth + 2);
            rotate([0, 0, 90])
                arch_cutout(16, 38, width + 2);
        }

        // Corner pillars with bottom interlocking holes
        for(x = [-peg_offset, peg_offset]) {
            for(y = [-peg_offset, peg_offset]) {
                difference() {
                    translate([x, y, 0])
                        cylinder(r=pillar_radius, h=height-wall_thickness);
                    
                    // Main hole
                    translate([x, y, -0.1])
                        cylinder(r=hole_radius, h=hole_depth+0.1);
                        
                    // Bottom chamfer to accommodate elephant foot and peg fillet
                    translate([x, y, -0.1])
                        cylinder(r1=hole_radius+0.8, r2=hole_radius, h=0.8);
                }
            }
        }

        // Top interlocking pegs
        for(x = [-peg_offset, peg_offset]) {
            for(y = [-peg_offset, peg_offset]) {
                // Main peg
                translate([x, y, height])
                    cylinder(r=peg_radius, h=peg_height);
                    
                // Base fillet for peg strength
                translate([x, y, height])
                    cylinder(r1=peg_radius+0.6, r2=peg_radius, h=0.6);
            }
        }
    }
}

figure_stage_riser();