Add lace to your window with cornstarch. Iron your lace and cut to fit. Mix 2 tbsp cornstarch with about an equal amount of cold water, then mix that in about a cup and a half of boiling water. Paint a thick layer on the window pane. Then apply another thick layer on top using random brush strokes being sure to get all the corners. To remove it, you just wash it off with warm water,
Make a cornflour podge (aabout 2 tablespoons cornflour mixed with about an equal amount of cold water. Add to about a cup and a half of boiling water from the kettle. Use the resulting jelly to paint a thick layer onto the window pane. Cut out a rectangle of ironed lace using a template. Paste onto the pane, and cover with another layer of podge. Leave to dry. Wash with warm water to remove.