In this project I have build in less than an hour a castle for my kids to play with their knights.

Easy to do with daily tools and material. No need of special tools or supply.

I love cardboard so I decided to upcycle a delivery cardboard box and a cardboard tube (I found it at my office A0 printer as it is used to deliver the paper roll into the printer)

I am writing this Instructables long-time after actually building the castle, so some pics might be missing. Please let me know if some steps are unclear. It proves by the way that the design is "childproof" ;-)

What you will need:

- a cardboard box such as a moving box, dimensions are free as long as they are suiting your children toys ;-)

- a cardboard tube, wide enough to serve as guard towers (again, choose it according to the size of the toys),

- a utility knife,

- a cutting mat or a sacrificial piece of cardboard,

- hot glue gun with hot glue (much easier) or white glue/wood glue,

- gummed paper/kraft

- a ruler

- a pencil

- a small screwdriver

Step 1: Build the Walls

First define the height of your castle depending of the toys height.

Draw 2 lines on the cardboard box (make it flat, it is easier) to cut the crenelated way.Take your pencil and ruller and draw marks where you will remove the cardboard, creating your crenelated parapet.

My walls were about 13 cm high with 3cm x 3cm crenelates.

Cut the box at an appropriate height in order to obtain the walls of your castle.

Let's now do the annoying part of the project: cutting the battlement or crenelated parapet. On the upper side of the remaining part of the box, let's cut your parapet. It is the part that take most of the time building this castle. However, do it with care and attention as the quality of the parapet will be key to the aesthetic of the castle.

Once done, take your cardboard tube and cut the towers out of it.

Step 2: Build the Towers

First measure the total length of your tube as it will define if you can make several towers out of it. If you can have 1à cm higher than the walls towers out of it, you're done. My tower are about 23 cm high.

Use the utility knife or a hacksaw, depending of the thickness of the tube.

One can make a door as the bottom of one tower as an entry for the treasuries room.

As you have to make a floor for your towers for the defendants to stand, report on a piece of cardboard box cuttings, the outer diameter of your tube and cut the round, taking care to be a bit (but just a bit) smaller than the actual diameter. Make a floor for each tower. Using the Hot glue gun or wood/white glue, glue the floor on the top of each tower according of the size of the knights.

Take each tower and apply some hot glue or white/wood glue on the outer diameter in order to the glue line to fit the inner part of your box /walls. Glue a tower at each angle of your castle using this technique.

Maintain the tower and the wall in contact the time required for the glue to cold/dry.

Step 3: Main Door and Covered Way

Main door

Using the pencil, trace the shape of the main door on one of the wall, cut it with the utility knife. Using a small screwdriver pinch 2 holes on the door and 2 holes on the wall to make a wire path, opening and closing the door like the ancient knights did.

Covered way

Using a ruler, take the exact dimension between 2 towers and cut a band of the remaining cardboard to make the covered way.

Fix it to the wall and towers using the gummed kraft. Don't forget to put gummed kraft under the way. Fold the kraft before humidifying it to allow a better fit.

If you feel it, one can now paint the castle to make it more beautiful.