Sandpaper an unfinished, wooden desk, then paint the entire desk white. Let dry.
Trace two turret shapes onto a sheet of plywood with a pencil. The height of each turret should be two feet taller than the height of the desk. The shape is a wide rectangular column with a triangle shape at the top of each turret, making it look like the top of a castle.
Cut out each turret from the plywood using a hand saw. Smooth the edges of each shape with sandpaper. Paint each turret white and let dry.
Add paint details to each dried turret. Paint just the triangle part a pastel color like pink or purple. Use a neutral color like gray to paint a brick pattern on the columnar part of each turret. Let dry.
Attach the turrets to the desk using a hammer and nails. One turret should go on either end of the back side of the desk.
Hot-glue fake vines to the bottom of the desk to simulate the bottom of a castle.