Instructions:

1. Cut flaps of box, save these for turrets.  Draw even number of squares along top edge of the box, on every side, and cut these out.
2. Draw windows and door on castle, also cut these out.  Roll flaps into tubes for turrets, also cut squares out of top edge of these and stick these on with masking tape.  Paint entire castle in chosen colour.
3. Use contrasting colour to sponge on brickwork using small rectangle of foam.  Make flags by concertina folding sequins mesh.  Thread these onto small length of pipecleaners + stick on with masking tape.

All items (or similar) are available from Play Resource Shop & Scrapstore.