Task: Draw a cuboid
C#: using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;

namespace Cuboid
{
    public partial class Form1 : Form
    {
        double[][] nodes = {
            new double[] {-1, -1, -1}, new double[] {-1, -1, 1}, new double[] {-1, 1, -1},
            new double[] {-1, 1, 1}, new double[] {1, -1, -1}, new double[] {1, -1, 1},
            new double[] {1, 1, -1}, new double[] {1, 1, 1} };

        int[][] edges = {
            new int[] {0, 1}, new int[] {1, 3}, new int[] {3, 2}, new int[] {2, 0}, new int[] {4, 5},
            new int[] {5, 7}, new int[] {7, 6}, new int[] {6, 4}, new int[] {0, 4}, new int[] {1, 5},
            new int[] {2, 6}, new int[] {3, 7}};

        private int mouseX;
        private int prevMouseX;
        private int prevMouseY;
        private int mouseY;

        public Form1()
        {
            Width = Height = 640;
            StartPosition = FormStartPosition.CenterScreen;
            SetStyle(
                ControlStyles.AllPaintingInWmPaint |
                ControlStyles.UserPaint |
                ControlStyles.DoubleBuffer,
                true);

            MouseMove += (s, e) =>
            {
                prevMouseX = mouseX;
                prevMouseY = mouseY;
                mouseX = e.X;
                mouseY = e.Y;

                double incrX = (mouseX - prevMouseX) * 0.01;
                double incrY = (mouseY - prevMouseY) * 0.01;

                RotateCuboid(incrX, incrY);
                Refresh();
            };

            MouseDown += (s, e) =>
            {
                mouseX = e.X;
                mouseY = e.Y;
            };

            Scale(80, 120, 160);
            RotateCuboid(Math.PI / 5, Math.PI / 9);
        }

        private void RotateCuboid(double angleX, double angleY)
        {
            double sinX = Math.Sin(angleX);
            double cosX = Math.Cos(angleX);

            double sinY = Math.Sin(angleY);
            double cosY = Math.Cos(angleY);

            foreach (var node in nodes)
            {
                double x = node[0];
                double y = node[1];
                double z = node[2];

                node[0] = x * cosX - z * sinX;
                node[2] = z * cosX + x * sinX;

                z = node[2];

                node[1] = y * cosY - z * sinY;
                node[2] = z * cosY + y * sinY;
            }
        }

        private void Scale(int v1, int v2, int v3)
        {
            foreach (var item in nodes)
            {
                item[0] *= v1;
                item[1] *= v2;
                item[2] *= v3;
            }
        }

        protected override void OnPaint(PaintEventArgs args)
        {
            var g = args.Graphics;
            g.SmoothingMode = SmoothingMode.HighQuality;
            g.Clear(Color.White);

            g.TranslateTransform(Width / 2, Height / 2);

            foreach (var edge in edges)
            {
                double[] xy1 = nodes[edge[0]];
                double[] xy2 = nodes[edge[1]];
                g.DrawLine(Pens.Black, (int)Math.Round(xy1[0]), (int)Math.Round(xy1[1]),
                        (int)Math.Round(xy2[0]), (int)Math.Round(xy2[1]));
            }

            foreach (var node in nodes)
            {
                g.FillEllipse(Brushes.Black, (int)Math.Round(node[0]) - 4,
                    (int)Math.Round(node[1]) - 4, 8, 8);
            }
        }
    }
}

Go: package main

import "fmt"

func cuboid(dx, dy, dz int) {
    fmt.Printf("cuboid %d %d %d:\n", dx, dy, dz)
    cubLine(dy+1, dx, 0, "+-")
    for i := 1; i <= dy; i++ {
        cubLine(dy-i+1, dx, i-1, "/ |")
    }
    cubLine(0, dx, dy, "+-|")
    for i := 4*dz - dy - 2; i > 0; i-- {
        cubLine(0, dx, dy, "| |")
    }
    cubLine(0, dx, dy, "| +")
    for i := 1; i <= dy; i++ {
        cubLine(0, dx, dy-i, "| /")
    }
    cubLine(0, dx, 0, "+-\n")
}

func cubLine(n, dx, dy int, cde string) {
    fmt.Printf("%*s", n+1, cde[:1])
    for d := 9*dx - 1; d > 0; d-- {
        fmt.Print(cde[1:2])
    }
    fmt.Print(cde[:1])
    fmt.Printf("%*s\n", dy+1, cde[2:])
}

func main() {
    cuboid(2, 3, 4)
    cuboid(1, 1, 1)
    cuboid(6, 2, 1)
}