Launch It: the Paper Catapult.

Give all your classmates or co-workers copies of the template - declare war over lunchtime...

Step 1: Materials and Tools

This is a cut-out-and-make Instructable.

You need a copy of the template (I work to A4), a cocktail stick, scissors and a glue-stick to make each catapult (though sticky tape may be useful for battle-field repairs). A cutting mat is a lot of help if your work bench is a s rough as mine (my mat is marked in 1cm squares, which gives you an idea of the sheer size of this great weapon).

New for 2009, at no extra cost! A redrawn PDF file of the template is now attached to this step!

The ammunition can be anything that will fit in the catapult's bucket - paper balls, the rubbers off pencils. I shot Tic Tacs at my class - if they caught them before they hit the floor, they ate them.

Safety

A pad of paper towel or modelling clay will stop you skewering yourself when you poke the necessary holes in the paper.

Full personal safety precautions can be seen in the video in step five.

Step 2: The Throwing Arm.

We'll do the hardest single piece first.

The throwing arm has two ends (doh!), which both need folding properly to make it work.

1. Cut out the arm (cut all solid lines, score all dotted lines), and use the cocktail stick to pierce holes at the dots.

2. Fold the whole thing into a square-section beam. Glue the full length of the flap and allow to dry. You will be able to tell which way up the beam goes by looking at the writing down the sides.

3. At the "flippy end", fold the two narrow flaps over and glue their outsides. Fold the long central flap over the narrow flaps and pinch gently along the corners to make it stick. Glue under the end of the long flap to stick to the underside of the arm.

4. At the bucket end of the arm, there is a flap connected to the top surface of the beam. Glue under the end of the flap, and press it down into the beam - it should stick to the inside of the lower face of the beam, and block off the end of the beam at the same time, preventing ammunition slipping down inside the arm, which would be inconvenient.

5. Glue the outside face of the two side flaps and fold them over to make the back / end of the bucket. You should have one flap left - lift it up and stick to the outer side of the two flaps you just glued.

The arm is done. Set it aside for now.

Step 3: The Base.

Rather than create a base in five parts, I have chosen to design it in one piece. This makes the corners more rigid, and reduces the number of pieces lost when you sneeze at just the wrong time.

Cut and crease the template, then start at the long sides - the sides fold up, inwards, down and then towards the centre of the frame. Glue the last pasrt down to the base of the frame.

When you have glued both sides, work on the ends. The first fold up seems to leave two extra bits sticking out at the sides. They're supposed to be there - glue them to the outside of the sides of the base. As you fold it over the top, glue the end down onto the sides of the base.

Two longer flaps glue to the tops of the side beams.

The ends then fold down inside the same way as the long sides. Glue them down, and then set the base aside to dry.

Step 4: The Frame.

The frame that supports the arm has four beams - two vertical and two diagonal.

The Vertical Beams

Cut and crease - note that the flaps at one end of the beam do not all get creased.

Glue the long flap and fold the piece into a square-section beam. Make sure the three holes line up (you should have just glued one hole over another).

Pierce holes at the three dots, then glue the outside of three of the flaps at the end with the dots. Fold the three glued flaps on top of each other, then cover the third glued flap with the fourth, dry flap.

At the other (lower) end of the beam, glue one of the creased flaps, fold it down, and fold the opposite flap on top of it.

You should now have a beam with two flaps sticking out at one end.

Repeat with the other beam.

The Diagonal Beams

Cut and crease.

Glue the long(ish) flap, and fold the piece into a square-section beam. You should have six loose, unglued flaps.

Repeat with the other diagonal beam.

Step 5: Construction.

Time to put the whole thing together.

Lay the base on your workspace, "beams up".

Take one vertical beam, and glue the insides of the loose flaps. Stand it near one end of the base, with the flaps astride the beam (see photo). Press the flaps into place for a few seconds, then repeat with the other vertical beam. Before the glue has a chance to dry properly, thread the cocktail stick through the holes you pierced yo make sure they are all in line (you should be able to slide the second beam a little bit if you need to, before the glue dries).

Take one of the diagonal beams and glue the insides of all six flaps. Set it against the side of one of the vertical beams, with the four narrower flaps astride the vertical beam and the beam of the base. The end flaps should be pressed into place against the vertical beam and the base beam.

Repeat with the other diagonal beam on the other vertical beam.

Hold the firing arm between the tops of the two vertical beams (make sure it's the right way up!) and thread the cocktail stick back through the whole lot - both vertical beams and the arm.

You need to give the joints a little time to set again, but otherwise you're finished.

Load up the bucket with the ammunition of your choice, and LOOSE!

Step 6: Template.

If you're not a "pro account" holder, you won't have actually seen the template yet.

Here it is - enjoy.